I've tested this and it's worked for me every time. But others are reporting that it doesn't necessarily work as intended. I believe it's going to be due to where you pick up the blueprints.
Anyways, when you go back to the waiting room, go up to the BP guy, but don't talk to him. Instead, go into your inventory and discard/drop all but one BP you're carrying. Your character will place them on the ground, so you aren't getting rid of them. Note - you should probably be far enough away from the counter to prevent your dude from clipping them into the counter, because I could totally see that happening.
So once you've only got one ??? BP in your inventory, talk to the guy. He will ID it. Pick up one ??? BP and do it again. Repeat until your BP stash is empty.
In theory, this should help you get new items every time. However, depending on how BP spawns work and how the system actually works, you may not. My thoughts are that some BP spawns are static and some are random. I think static spawns are decided when you pick them up in the tower but that random spawns are determined when you talk to the guy in the waiting room while holding BPs in your inventory. Almost like it assigns an ID to the BPs in your inventory once you speak to him.