The jelly roll I used had some duplicates in it and I thought my top came out just fine. It's really up to you. Some of of the same strips ended up on top of each other but always off-set and not stacked directly above each other, so you still get a scrappy look. It's a fun quilt to make! The first one I ironed as I sewed, the second I waited until the top was all sewed to iron. My preference is to iron as you go! Took too long to iron the whole top at once! But that's just me! Have fun!