I run a 1e game (Hyperborea) with 6 players. From that group (counting me), 3 started with 0e, 1 with 1e, 1 with 2e, 1 with 3.5 and one with 5e. Everyone in that group plays in an alternating 5e game (I play instead of DM in that one).
I run another 5e game, again with 6 players.
I know of...