Here's a partial list of Theorytabs that are duplicates of each other, i.e., somebody uploaded a tab for a song that already exists, but with a different title or a misspelling. Correct tab is first, mistakes are in bold.

Memories by David Guetta: http://www.hooktheory.com/theorytab/view/david-guetta/memories
Memories by Getta: http://www.hooktheory.com/theorytab/view/getta/memories

Hold On We're Going Home by Drake: http://www.hooktheory.com/theorytab/view/drake/hold-on-were-going-home
Just Hold On Going Home by Drake: http://www.hooktheory.com/theorytab/view/drake/just-hold-on-going-home

The Lion Sleeps Tonight by The Tokens: http://www.hooktheory.com/theorytab/view/the-tokens/the-lion-sleeps-tonight
Lion Sleeps Tonight - In the Jungle by The Tokens: http://www.hooktheory.com/theorytab/view/the-tokens/lion-sleeps-tonight---in-the-jungle

Strong by London Grammar: http://www.hooktheory.com/theorytab/view/london-grammar/strong
Str by London Grammar: http://www.hooktheory.com/theorytab/view/london-grammar/str

Boss Mode by Knife Party: http://www.hooktheory.com/theorytab/view/knife-party/boss-mode
Knife Party by Boss Mode: http://www.hooktheory.com/theorytab/view/boss-mode/knife-party

You Got 2 Let The Music by Capella: http://www.hooktheory.com/theorytab/view/capella/u-got-2-let-the-music
You Got 3 Let The Music by Capella: http://www.hooktheory.com/theorytab/view/capella/u-got-3-let-the-music

Don't Speak by No Doubt: http://www.hooktheory.com/theorytab/view/no-doubt/dont-speak
gd by as: http://www.hooktheory.com/theorytab/view/as/gd

Got U Under - Spisek Jednego Remix by XXANAXX: http://www.hooktheory.com/theorytab/view/xxanaxx/got-u-under---spisek-jednego-remix
Under My Skin - Spisek Jednego Remix by XXANAXX: http://www.hooktheory.com/theorytab/view/xxanaxx/under-my-skin---spisek-jednego-remix

Big Bang Theory Theme Song by Bare Naked Ladies: http://www.hooktheory.com/theorytab/view/bare-naked-ladies/big-bang-theory-theme-song
Big Bang Theory by Bare Naked Ladies: http://www.hooktheory.com/theorytab/view/bare-naked-ladies/big-bang-theory
(These were both made by the same person, and both are missing video)

Oblivion by M83: http://www.hooktheory.com/theorytab/view/m83/oblivion-
Oblivion by M83: http://www.hooktheory.com/theorytab/view/m83/oblivion
(Here the titles and artists are identical, but one URL has a dash at the end so they became separate tabs)

In My Mind by Ivan Gough and Feenixpawl: http://www.hooktheory.com/theorytab/view/ivan-gough-and-feenixpawl/in-my-mind
Payback by Steve angello: http://www.hooktheory.com/theorytab/view/steve-angello/payback
(The second tab is a duplicate of the first, but with the title of a completely different song)

Three different versions of "A Whole New World":
A Whole New World by Aladdin: http://www.hooktheory.com/theorytab/view/aladdin/a-whole-new-world (this one was first)
A Whole New World by Disney: http://www.hooktheory.com/theorytab/view/disney/a-whole-new-world (this one has a better title)
Disney by A Whole New World: http://www.hooktheory.com/theorytab/view/a-whole-new-world/disney (mistaken upload by the author of the previous one, then edited by someone else)

Somebody listed themself as the artist for 5 songs, all of which are already on Theorytab:

Flight by Tristam and Braken Monstercat: http://www.hooktheory.com/theorytab/view/tristam-and-braken-monstercat/flight (doesn't need Monstercat at the end by the way)
Flight by Nulty09: http://www.hooktheory.com/theorytab/view/nulty09/flight

Mozart by Mat Zo and Arty: http://www.hooktheory.com/theorytab/view/mat-zo-and-arty/mozart
Theme 1 by Nulty09: http://www.hooktheory.com/theorytab/view/nulty09/theme-1

Can't Hold Us by Macklemore and Ryan Lewis: http://www.hooktheory.com/theorytab/view/macklemore-and-ryan-lewis/cant-hold-us
Can't Hold Us by Nulty09: http://www.hooktheory.com/theorytab/view/nulty09/cant-hold-us

American Dad - Theme Song by Walter Murphy: http://www.hooktheory.com/theorytab/view/walter-murphy/american-dad---theme-song
American Dad by Nulty09: http://www.hooktheory.com/theorytab/view/nulty09/american-dad

Too Many Cooks Theme Song by Adult Swim: http://www.hooktheory.com/theorytab/view/adult-swim/too-many-cooks-theme-song
To Many Cooks by Nulty09: http://www.hooktheory.com/theorytab/view/nulty09/to-many-cooks

Other tabs with wrong or reversed titles:

Innocence ft Mark Foster by Madeon: http://www.hooktheory.com/theorytab/view/madeon/innocence-ft-mark-foster
(should be Nonsense ft Mark Foster)

Bang Bang Bang by Jessie J and Ariana Grande ft Nicki Minaj: http://www.hooktheory.com/theorytab/view/jessie-j-and-ariana-grande-ft-nicki-minaj/bang-bang-bang
(should be Bang Bang)

Unknown by Flea Waltz: http://www.hooktheory.com/theorytab/view/flea-waltz/unknown
(should be Flea Waltz by Unknown)

If you come across more of these, or accidentally mistitle a tab, feel free to post a link to it here.

What about the many tabs by ZUN that are supposed to have a tilde (~), but because we can only use alphanumeric and a select few other characters, we have to use a dash (-)?

Everything below needs the space-dash-space to be replaced with a space-tilde-space:

ZUN
A God that Loves People - Romantic Fall
Akutagawa Ryuunosuke's Kappa - Candid Friend
Catastrophe in Bhava-agra - Wonderful Heaven
Cemetery of Onbashira - Grave of Being
Copse Voyage - Be of Good Cheer (Needs both tilde and exclamation point at the end)
Crimson in the Black Sea - Legendary Fish
Doll's Story - Doll of Misery
Gensokyo Past and Present - Flower Land (should be Gensokyo, Past and Present ~ Flower Land. Needs comma)
Girl's Divinity - Pandora's Box
Hiroari Shoots a Strange Bird - Till When
Kobito of the Shining Needle - Little Princess (New translations turn kobito to inchling, but both are correct)
Last Occultism - Esotericst of the Present World
Lunatic Eyes - Invisible Full Moon
Mystical Oriental Dream - Ancient Temple
Paradise - Deep Mountain
Pure Furies - Whereabouts of the Heart
Reach for the Moon - Immortal Smoke (change dash to comma)
Satori Maiden - Third Eye
Shoutouku Legend - True Administrator
Solar Sect of Mystic Wisdom - Nuclear Fusion
Spring Lane - Colorful Path
The Great Fairy Wars - Fairy Wars
The Road of the Apotropaic God - Dark Road
The Sealed-Away Youkai - Lost Place
Touhou 5 Mystic Square - Alice in Wonderland (Should only be "Alice in Wonderland")
Unknown X - Unfound Adventure
Vanishing Dream - Lost Dream

Wan Wan
Life Guiding Song -Prospect Mirai (Should be space-tilde-space, my fault here)
Sky-Filling Departed Spirit - Lightning Word

Thinkin Bout You by Frank Ocean; one has a leading space:
http://www.hooktheory.com/theorytab/view/frank-ocean/thinkin-bout-you
http://www.hooktheory.com/theorytab/view/frank-ocean/-thinkin-bout-you
(could merge "Chorus" from incorrect title into correct title)

The Way It Is by Bruce Hornsby: http://www.hooktheory.com/theorytab/view/bruce-hornsby/the-way-it-is
Bruce Hornsby by The Way It Is: http://www.hooktheory.com/theorytab/view/the-way-it-is/bruce-hornsby
(could merge "Intro" from incorrect title into correct title)

Love On Top by Beyonce: http://www.hooktheory.com/theorytab/view/beyonce/love-on-top
Beyonce by Love On Top: http://www.hooktheory.com/theorytab/view/love-on-top/beyonce
(can delete incorrect one, it's already copied to correct title)

Let Me Go by Avril Lavigne; one has a leading space:
http://www.hooktheory.com/theorytab/view/avril-lavigne/let-me-go
http://www.hooktheory.com/theorytab/view/avril-lavigne/-let-me-go
(both have a "Verse" section, the one from the leading-space version is more complete and should be kept if possible)

Take Flight by Kevin Macleod: http://www.hooktheory.com/theorytab/view/kevin-macleod/take-flight
(should be by Craig Austin, the youtube video is misattributed)

Mulan - Relfection by Disney: http://www.hooktheory.com/theorytab/view/disney/mulan---relfection
(should just be "Reflection", for consistency with other Disney songs, and also spelled correctly)

Thanks all for your help in identifying these errors. I will start working through these. Also on our list: creating an "Admin" user class that can do this, so you don't have to bug us on the forums

-Dave

Also on our list: creating an "Admin" user class that can do this, so you don't have to bug us on the forums

Which you guys need to be, since you are the owners and founders...

Down Under by Men at Work http://www.hooktheory.com/theorytab/view/men-at-work/down-under
Land Down Under by Men at Work http://www.hooktheory.com/theorytab/view/men-at-work/land-down-under

Bumping this thread to post my own mistake:
Capcom by Okami - Reset should be Okami - Reset by Capcom

Beloved My John by Sufjan Stevens should be merged with "John My Beloved" (which also exists, with different sections)

all of the examples in this thread have been fixed.

Thanks

Toby Fox by Undertale- Wrong Number Song -Cover by DM Dokuro- should be Undertale - Wrong Number Song - Cover by DM Dokuro by Toby Fox

U N Owen Was Her should be U.N. Owen Was Her?

With question mark

Please merge http://www.hooktheory.com/theorytab/view/snakehips/all-my-friends-ft-tinashe---chance-the-rapper and http://www.hooktheory.com/theorytab/view/snakehips/all-my-friends. My fault for not checking before transferring!

This is interesting:

Chandelier shows up twice on Sia's artist page, once with a trailing hyphen, but both links go to the version with hyphen. They can both be navigated to directly, though:

http://www.hooktheory.com/theorytab/view/sia/chandelier
http://www.hooktheory.com/theorytab/view/sia/chandelier-

The contributor list appears to be incorrectly jumbled between the two pages. IMO I'd keep the two sections being displayed on the with-hyphen page, and delete the two from the non-hyphen page.

---

Three copies:
http://www.hooktheory.com/theorytab/view/pitbull/timber-ft-kesha
http://www.hooktheory.com/theorytab/view/pitbull/timber-feat-kesha
http://www.hooktheory.com/theorytab/view/pitbull-feat-kesha/timber

Please delete
http://www.hooktheory.com/theorytab/view/all-my-friends-ft-tinashe---chance-the-rapper/snakehips
and
http://www.hooktheory.com/theorytab/view/snakehips/all-my-friends

They are duplicates of the correct version at
http://www.hooktheory.com/theorytab/view/snakehips/all-my-friends-ft-tinashe---chance-the-rapper

Delete: http://www.hooktheory.com/theorytab/view/tom-petty-and-the-heartbreakers/-i-wont-back-down
Duplicate of: http://www.hooktheory.com/theorytab/view/tom-petty-and-the-heartbreakers/i-wont-back-down

Mountain of Faith - Player's Score should be just Player's Score. My fault on that one.

http://www.hooktheory.com/theorytab/view/derrick-harriot/let-me-down-easy <-- Misspelled artist name/accidental capitalization
http://www.hooktheory.com/theorytab/view/the-killing-moon/echo-and-the-bunnymen <-- Swapped song/artist

Both tabs have versions with the correct title already in the database.

Fate of 60 Years should be Eastern Judgement in the Sixtieth Year ~ Fate of Sixty Years due to title length restraints.

I am not sure if this is a title mistake or a glitch, but:

http://www.hooktheory.com/theorytab/view/hyadain/hyadains-o-o-o-one-sided-love-c---nichijou-op-1

This tab features the correct artist name. However, when edits where made to this tab, there was somehow a second duplicate created which has the artist name with a hyphen at the end.

http://www.hooktheory.com/theorytab/view/hyadain-/hyadains-o-o-o-one-sided-love-c---nichijou-op-1

The tab with the hyphen is the most recent tab, and the other should be removed, and the artist name corrected on the second.

(This duplicate: http://www.hooktheory.com/theorytab/view/hyadain/hyadain-no-kakakata-kataomoi-c unrelated to this bug should also be removed)