Couch co-op individual loot unbalanced?

My girlfriend and I only play in offline couch co-op mode. I play a Barb currently at L67 and she plays a Wizard at L69. We're playing ROS on Xbox360.

What we've noticed is that often a chest or treasure goblin or even a low-level boss (champion?) will spit out a lot of loot that goes only to me (that is, it's designated as mine and goes to my character, no matter who picks it up). I'm almost always player 1, but last night, we set her as player 1 thinking that might make a difference, but it didn't.

This happens easily >50% of the time - I get all, she gets bupkus. There's been very few times where SHE got all of the loot, with the remainder more or less evenly distributed between us. It's not just rare or legendary loot - we've seen loot piles that ended up being almost all gems that still all went to me.

Since we've eliminated the possibility that everything is going to Player 1, is it possible that I'm getting all of the loot because my level trails hers a bit? What other factors would contribute to this?