Well I got nine!
...total. Two this pass.
I do have a working theory that the cornucopia drops AREN'T entirely random. I think your chance of getting one is higher when there's live enemy turkey tanks on the board.
. . .can't actually test that 'till next reset though. Also trying to avoid killing them is difficult. You can tell I'm getting bored with something when I start making up challenge mode crap like this.