Oh, yes I see new changes in playchoice bios.
Checked in mameplus and mamefx (in mame32 should be too, because it's bios change).
Right mouse click on game -> Properties -> Miscellaneous -> BIOS -> Single Monitor Version
or
Right mouse click on game -> Properties of playch10.c -> Miscellaneous -> BIOS -> Single Monitor Version
or
Options -> Default Game Options -> BIOS -> Play-Choice 10 BIOS -> Single Monitor Version