Question about Target exchange policy re: B2G1

I took advantage of the sweet B2G1 free deal at Target last week. I have an unopened game, and have been considering returning it for another title. The cost on the receipt, per title is $40. Anybody know if I would be able to exchange it straight-up for another full-retail cost title, like BioShock Infinite, or would I need to pay the $20 difference? Thanks!

You will get the refund amount back if returning - so $39.99. As per policy, you can only exchange for same title. Very YMMV but you may be able to exchange for another game with the same pre discount price.

Thanks! I figured that was probably the case.