Did you know that you can halftone dither two different but same size QR codes on top of each other?

I wish I had a link to the article handy, but yeah I've tried that myself and it totally works! You basically get a 50/50 chance of one or the other code scanning. It's literally two QR codes in one!

And no, that's not some new special QR code format either, it's basically taking advantage of the nature of the scanners plus the built in error correction.