Since this is related to ROMs, I'll move it over to the Emulation forums, as it's the better fitting place.
There are different dump versions of the games. 1.0 is the first, initial dump. If some errors were found in it, other release groups, or the same, make a second dump of the game, the version 1.1.
The list goes on and on, but usually every errors are fixed in the 1.2 version, so no further dumps are needed.
The differences for cheaters or hackers are that the offsets of things changed, so cheat codes or programs won't work on those ROMs, unless they're adjusted.