Which movie do you own the most copies of?
In my case, it's (by a wide margin) Terminator 2: Judgement Day.
When I began collecting DVDs in 1998, of course I bought the first version of T2 I could get, since it was (and still is) my favorite movie.
That DVD release wasn't very good compared to other DVD releases of that time. Sure, the picture was crisper than the VHS cassette I copied from a video-store-rental and it had Dolby Digital 5.1 sound. But it only had 2 German audio tracks (DD5.1 + Stereo), no other languages, not even the original English audio track. And a much as I liked the 2.35:1 widescreen aspect (my VHS copy was cropped 4:3 or 16:9) it wasn't anamorphic widescreen but lower resolution "letterboxed" widescreen.
I don't know what happend to that disc... maybe I sold it or gifted it to a friend when I got better versions later.
In the following years I bought the American and the German "ultimate" editions. After that the "extreme" edition released on DVD. Then the HD-DVDs followed with awesome 1920x1080 resolution.
I skipped the Blu-ray version at first, but in 2017 I was very hyped about the return of Terminator 2 into the cinemas as 3D-version. Of course my buddies and me watch it on the big screen (again), this time in stereoscopic 3D. A few month later I got the Blu-ray 3D, which also included the 2D version on Blu-ray.
And finally(?) in 2021 I got the "30th anniversary edition", which included the Blu-ray, the Blu-ray-3D and the 4K-UHD.
So now I can choose between 3 DVD versions, 2 HD-DVD versions, 2 Blu-ray versions, 2 Blu-ray-3D versions, and 1 UHD version, when I want to rewatch it again. 
