first, let me create a scenario

iv'e got a soldier (no specific soldier) with psychic ability `mind control`. he is facing 2 enemies, namely a muton and a sectopod. iv'e used `mind control` on the muton and succeded. i ended the round and as usual, the muton is flanked by the sectopod and killed the muton. iv'e killed the sectopod and the round finishes, thus winning it. at the rewards iv'e received are `plasma rifle`, `plasma pistol`, and a `alien grenade`along the 6 weapon fragments(yup, iv'e calculated it).

so, is this a bug? take note that i didn't even bring an arc thrower in this mission because iv'e interrogated every alien at this point.