At least one of the workouts during the two-a-week OHP could be DB. That's how I always try to do mine...one day DB, the other BB if I'm hitting it twice a week. I don't know about both days...I think that's something you'll have to try and see for yourself.

Personally during that week I would start the first bench workout with BB bench press and then follow it (maybe some other minor accessory exercise in between) with DB OHP. Then the second bench day I would start with BB OHP and then do DB bench. It's hard to increase if all of your OHP is done while you're fatigued so moving it to the front of the line should allow you to move more weight.