Challenged to a Question I've already made predictions on.

I received a challenge on a question that I've already made predictions on and Hubdub still wants me to predict or decline the challenge. I was thinking that perhaps challenges could check the person's open predictions, so you're not receiving a bunch of challenges to questions you already have cash on. I don't know how often this happens, I only have 2 friends so I'm not really receiving challenges left and right, but other people might be. It's just a thought, but I figured I'd throw it out there.

Then again this is probably one of the reasons there's a 'Decline' button.