Crossing your eyes until the images overlap is the key to any of these that you can lay side-by-side. Also works when comparing what's been changed between two documents.
I laughed out loud about 5 different times that Baka messed up the photo editing. Nice to see the original three interaction after the last two chapters.
@DjAlexDubCheck
I blended the pictures using an XOR filter.
A "Difference" filter would've worked too, and would've looked like this:
Difference works well here because manga use mostly black and white.
The difference between white (255) and black (0) is also white (255).
However, it doesn't work very well for similar colors. For instance, gray (128) and dark gray (100) would result in near-black (28).
XOR can make even slight differences very obvious. In the case of gray (128) and dark gray (100) the result would've been near-white (228). That's why I prefer XOR.