1

I see Saturn games listed as M1 M2...Mn
What does it mean? Any link i can read? Thanks!

You mean 1M, 2M, etc.

it relates to the mastering code for the disc.

Here's an example of a Game disc where multiple pressings / masters exist
1M
http://redump.org/disc/3248/
2M
http://redump.org/disc/24292/

in most if not all cases the only difference is that the Audio tracks are shifted slightly differently (offset)

note how the hashes for the data track are identical.

3

I'm not sure what that is "mastering code".
Should i prefer 2M vs 1M or is there no difference from a player standpoint?

No ingame differences, it's just different copies of the game have audio data shifted differently. The ones with ingame differences are revisions (Rev A/Rev B/Rev C, etc.).

5

OK Thanks both!