I bought the Criterion Blu-ray of Kagemusha at Borders (couple years ago, obviously), despite (as I realized when I got home) having already bought a copy from the previous Barnes & Noble Criterion sale. Stupidly, I tore the shrinkwrap off right as I got home, then went to put it on my shelf and found another copy waiting for me.

just did it today with Rounders! i swear i can't remember some of these titles. that can't be good...

Still haven't done this, though I've done the opposite, where I'll pass on buying a blu-ray, assuming I have it when I don't.

I've done that once or twice.

I did this recently when I saw a copy of the 40th Anniversary digibook version of A Clockwork Orange at best Buy for $9.99. I bought it, brought it home and then discovered that I already had a Kubrick triple pack with that, 2001 and The Shining at home. This was a re-release with new documentary so I ended up keeping it anyway, but I might not have gotten it if I had known that.
Nothing is as dangerous as cheap Blu Rays on Black Friday. I don't know what I've bought half the time.

Recently i rented Parker with Jason Statham and then found it on my shelf a few weeks later. Don't remember ever buying it and hadn't opened it yet.

Just the other day, I was sitting on the floor, organizing my Blu-rays, and saw Rounders sitting there. I thought, "Oh... I guess I DID buy that one!" because I sure as hell don't remember ever buying it.

I use the bluray.com phone app if I'm ever in question. But most of the time, I can usually remember.

I've done it a few times. lol

This still only has happened to me only once because of not declining a featured title from the Disney Movie Club and I wound up with two copies of The Muppets as I had already bought it in store.

I've never purchased anything I've already owned but I have rented things on amazon or vudu that I forgot I owned.

Haven't done it yet with Blu-ray, but I did do it with DVDs. I bought 25th Hour twice. Went to put it on my shelf, and 'ohhh, crap!'

I've had times where I've been looking at my collection and come across movies that I don't remember buying or being given.

Haven't re-bought anything that I can remember, but there have been times where I am standing in Best Buy contemplating a purchase, but can't remember if I already own it or not.

No

(both DVD & Blu-Ray)

That is incredibly sad that you started this thread and I have counted at least 3 times you have done it. AND Rounders no less...

And no I have never done it. Or with a DVD.

Nope. The duplicates in my collection were bought knowing that I already had a copy, usually when I was buying a box set or something that included a movie I already had as a single release.

I bought a duplicate on purpose if I wanted one sealed copy as a collector.

The only time I've done that is when I bought UK Stanley Kubrick Box set and I knew that meant owning a duplicate copy of The Shining, but since the US and UK cuts are different, I didn't feel bad about it.

There may be some truth in #2, but as for #1... arguably the best strategy (thrift) is surely WHY people wind up with doubles: you wait for a good deal, and when you find one you jump at it, since it's a good deal even if it is an accidental second copy. #3 is no real help - I watch things on TV, from friends and the library. Some/Many are good enough that I want my own copy "as and when" (#1), so it's films I HAVE seen that I'm searching for good deals on in many cases..!

That's closest to me, too. If I can find two different copies of the same film for less than the price of either, and thus have a better total package... it makes sense. IF I have the money, which is rare.

Mallrats was my latest acquisition for the 2nd time. and the kicker was i had my phone with me and my collection link. i could've easily checked and yet swore i didn't have it or ever bought it. even has the 90's slipcover on both. doh!