That's a great idea. I think it would probably work, but I can think of one potential case where it would introduce some complications.

If user1 sees 'pg' as the submitter and user2 sees 'blah' user1 might comment something which gives away that it is actually pg to user2. Now user2 might realize this and act on their pg bias.

Can you think of a way to prevent this?

Way:

group1 that contains user1 should be isolated from group2 that contains user2. They can't see each other's replies.

But I wouldn't want such things to happen here except on Apr 1.