reshowing a randomized selection

I'm wondering if anyone knows how I can show a random selection (4 out of a possible 6 items) and then reshow that same selection of 4 again? For example, I am trying to organize my survey so that users see a selection of 4 items, and then later they see the exact same 4 things and rate them. I have no problems with getting Qualtrics to show them 4 random items, but I can't figure out how to get Qualtrics to 'remember' the 4 shown, and then reshow them later on. Can anyone help?
Ryan