There’s four - two US, two Japan; the ones marked as the 1983 mix are from pan-and-scan LDs, and of those two the US one is the better source. The ones marked 1985 mix are from the Japanese Special Collection and the US Widescreen Edition, which was the debut of the 1985 mix for ANH and (maybe) ESB, but per Schorman, it’s the same mix as the 1983 theatrical mix. They’re presumably only included because whoever made the MKV package (williarob or ohteedee, I think) assumed a new mix was done for ROTJ in 1985, as most of us have for years.