[mikevin]

Do you have a writeup of the technical details? How does this exploit (without reading the code and reverse engineering it)?

[pmxi]

I'm not the author, but there's a brief explanation on the GitHub README:

(https://github.com/zacharyreese/DualQRCode)

The generator creates two separate QR codes with high error correction (Level H) and combines them into a single image using pixel splicing. Each cell that differs between the two QR codes is split in two, creating a pattern that can be interpreted differently based on the scanning angle.