I also kept all the Universal monsters single issues and double features when I bought the Legacy sets.

Warriors (Original release and the Ultimate Director's Cut)
Henry: Potrait of a Serial Killer (Original and 20th Anniversary Edition)
Sin City (Original and Recut. Extended. Unrated.)
Dawn of the Dead '78 (Divimax Special Edition and Zombi: Dawn of the Dead Divimax Special Edition)

I also own multiple copies of Night of the Living Dead, I have the Millennium Edition and several dollar bin copies. Every time I find a dollar copy I have to buy it.

I usually get rid of the old disc when a new one comes out that is better, but these I just haven't had the heart to do.

Donnie Darko (Theatrical & Director's Cuts)
Ed Wood (With & Without Cross Dressing Segment)
Halloween (25th Ann. & LE 2 Disc Theatrical/TV Cuts)
LOTR (TE's & EE's of all 3)
Night of the Living Dead (Elite Version & Colorized/B&W)
Terminator (Holofoil Cover & SE)
T2 (Extreme w/ Metal Slipcase & Ultimate w/ Metal Slipcase)
The Warrriors (DC & TC)

Two different copies of Mallrats. I only have my first copy since it's signed.

Yup...just another double dipster thread. And yup....I still have too many to sit here and list.

Hero (I have 3 versions including the Region 1, one of the Region 0s and the Region 0 director's cut), House of Flying Daggers (Thai Region 0 and Region 1), American Pie (Ultimate Rated and Collector's Unrated) and both the Extended and Theatricals of the LOTR trilogy.

Well, most double dippers get rid of the first copy, no?

Not always, no. Some special features may be missing and therefore both copies would be essential. If yer into that sort of thing. One example would be The Thing and the isolated score.

I usually sell mine on ebay when I do double dip which is rare. I'm getting ready to sell some since I found the superbit sale at BB.

I need to get rid of:
Spiderman Deluxe Edition
The Dark Crystal SE
Spiderman 2 SE
The Patriot SE

But the double dip was well worth...I love DTS tracks.

Lost Boys
Underworld
American Pie

The Last Samurai
Gladiator
The Fast and The Furious
Daredevil
Planet of the Apes (triple-dipped)
Underworld
Titanic
Dumb and Dumber
Alien vs Predator
Spider-Man
Spider-Man 2
Charlie's Angels
A Knight's Tale
Speed
xXx
Cowboy Bebop

Just T2 I think. There are few others that are worth keeping both releases for.

I've got two versions of Jaws and Halloween and the theatrical and extended versions of the LOTR trilogy and Underworld.

This isn't exactly the same as a double dip thread, as he's asking specifically if you're hanging on to two (or more?) versions of a movie.

I have both Daredevil's, the Signature and Extended Gladiator, Ghostbusters Collectors and then the Double Pack, as well as the original Sin City and the Recut version. Just been lazy to sell Ghostbusters and Sin City though.

I have Robocop CC and trilogy.

LOTR - extended and theatrical Cuts
The Good, The Bad and the Ugly - Original MGM release and extended version
Manhunter - Divimax Director's Cut, Japanese DTS real threatrical cut, Anchorbay LE with horrible quality director's cut and the workprint cut they misrepresent as the theatrical cut
Fistful of Dynamite - UK R2 SE and R3 editions
Halloween - Extended TV cut and 25th Anniversary edition

The following are not necessarily DVD duplicates
The Big Gundown - US theatrical cut and extended Italian cut
Bladerunner - International cut with voiceover Criterion LD and director's cut
Star Wars Ep 4-6 - current SE releases and LD of unadulterated trilogy
Superman I-III - Current DVD releases plus extended TV cuts

Let's see. I have the LE Japanese Kill Bill vol. 1 box set and the R1 single disc release. I also have to LE House of Flying Daggers Box sets, the wooden box version and R3 version. I have the old Titanic and the new just because havent dumped the old version yet. Both releases of Mulan, because I just cant seem to part with the older one, and I have the R1 collector's edition Pulp Fiction and the R@ French box set Pulp Fiction as well.

Lots of 'em, but as I go the old versions are being boxed up and I'm going to make a big haul into the pawn shop with them. A few are titles I'll keep both versions of, for instances where the new version lost some nifty features or extras.

Like many have said in earlier posts, I sell the old disc if I buy an upgrade (i.e., To Kill a Mockingbird, The Deer Hunter, etc...) But, if there is a significant difference (theatrical vs. director’s cut) or if the old disc is part of a box set, I’ll keep both.

Amadeus: theatrical & director's cut
Apocalypse Now: theatrical & “redux”
The Bank Dick: Criterion & Universal box set editions
Blade Runner: international & director's cut
Charlie Chaplin feature films (City Lights, Modern Times, etc...): Image & Warner editions
Das Boot: original & director’s cut
Dr. Strangelove...: original & 40th anniversary editions
The General: Image & Kino editions
Lawrence of Arabia: limited edition & superbit
The Love God?: original & Franchise releases
The Paleface: single & double-feature editions
Star Wars IV-VI: theatrical & "Lucas" editions
Universal Horror Classics (Frankenstein, Dracula, etc...): original & Legacy/Franchise releases
The Wizard of Oz: 3-disc collector’s & 1-disc box set editions

Akira
Alien
Apocalypse Now
Citizen Kane
Lord of the Rings

I usually dump inferior versions. I see no sense of owning a sub-standard disc. It's not gonna bring in much coin on the market, but I still dump them in my eBay store when necessary.

The only movies I've currently got two DVDs of are Leon: The Professional and Jaws. Over the last year, I parted with Clerks, Mallrats, Tommy Boy, and To Kill a Mockingbird, to name a few. I still need to dump Dumb & Dumber and Dead Poet's Society.

Where did you get the international cut on DVD?

Up until a few weeks ago, the only one I had was the original Matrix. I got the boxed set, and gave the single-disc to my sister. Other than that, I don't have two of anything.

Yeah, a few

Ghostbusters (kept original for extras)
LOTR trilogy (both versions of all three)
Dracula 1931 (classic monsters has different soundtrack from later release so I have both)
Abbott and Costello Meet Frankenstein (commentary track not on later Franchise set)
House on Haunted Hill (Roan version and Legend Films version for laughs)
Carnival of Souls (Criterion and Legend films for laughs)
Evil Dead II (Limited Tin and Book of the Dead)
Halloween (Limited and 25th for the different transfers and extras)
Good the Bad and the Ugly (still prefer the original cut so have both)
This is Spinal Tap (Criterion and MGM for the different extras)

I have double dipped on dozens of other DVDs, but sold the old versions in those cases as there was nothing worth holding on to the old one for.

Clerks
Heat
Get Shorty