Hmm interesting, but usually it seems that experience bombs say "experience bomb" and it's 10x the normal xp. This is the exact same ammount of xp, only it comes up twice. Sorta like the same thing with loot, sometimes you kill a single enemy but he drops double loot. I wonder if the game sometimes accidently writes two monsters into one, or considers one enemy two kills. It's all I can think of.