www.makemkv.com

Start with the title length - the box will say how long the movie is.

Anything more than a few seconds difference is NOT what you want. There will (usually) be a topic here that lists the length of the movie and which title comes up as right, but that's more often for BD and UHD nowadays than DVD.

The problem is that the title number is dependent upon what the person who posted the answer chose as their minimum file length. The title number is different if you choose 2:00 minutes (normal) vs. 1:30:00 (typical when searching for movies on disk).

I found the right one by matching playlist orders. But What I really want to learn how to do is find which one the blu ray player reads when I click 'play movie' on the menu. Haven't figured how to do that yet.
I suspect this will be a pretty common release strategy for a while.