From this disc's entry on
TheDiscDB it appears to have two main playlist files:
00800.mpls with the following segment map:
Code: Select all
62,107,71,108,73,109,75,125,69,110,78,111,80,112,82,113,84,114,86,115,88,116,90,117,92,118,94,119,96,120,98,121,100,122,102,123,104,124,106
and 00801.mpls with this segment map:
Code: Select all
62,70,71,72,73,74,75,76,69,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106
Assuming both files have the exact same runtimes and chapters, I'd guess they may be different language versions?
If you're working from a decrypted backup you could play some of the differing segments on your PC directly from the STREAMS folder, for example, you might play 00107.m2ts and 00070.m2ts to see if you can spot any difference (as they're right at the beginning of the movie I'd hazard a guess that they may be the movie's opening titles for alternate regions)?
Quite often the 00800.mpls file is the English language version (or the US version, or the Theatrical version) of a movie, and 00801.mpls, 00802.mpls, etc. are alternate versions, but it never hurts to double-check!
Sometimes the differences can be really hard to find, for example, there may be an English version using US spelling and an English version using UK spelling!
The only shadow of doubt cast over the above theory is that, in this particular case, I know "Avatar (2009)" has (at least) three different cuts available (according to
IMDb):
Theatrical: 162 min (02:41:41)*
Special Edition: 171 min (02:50:34)*
Extended Cut: 178 min (02:58:09)*
* The runtimes in brackets are from my own Blu-ray versions of the movie.
But if you say the runtimes of the files on the disc you have are identical than it likely isn't a different cut? Plus, nobody has reported more than one cut as being available on UltraHD (and I would've thought we'd hear about it if there were)!