I believe the system will take the amount of money off of the free game in that instance, however you can do a $20 off coupon plus any other amount besides $20. Hope that helps.
So I locked my trade in for taken king when it was high but never traded in bought some from Best Buy today with their dotd even though I missed the ship date I can still trade in correct? TIA
Cowboom has the PSTV for sale $49.99
http://m.cowboom.com/index.cfm?page=details&contentID=1578170&utm_campaign=cb-apr-10-2015&utm_medium=email&utm_source=Sony%20PlayStation%20TV%20System-text