Gunmen of the Apocalypse - S6-E3
Corrected entry: Although four bullets were fired (two from each shooter), only two bullets are heard falling to the floor...and the two bullets we see on the floor are perfectly formed and are not mutilated as they should be from hitting each other in mid air.
Correction: This isn't reality - you can't shoot bullets out of the air in real life. It's an AI game. Anything can happen.