P: Reference view (2 different files side by side)

Hey, Adobe! why isn't it here yet?!

It's a super handy feature to compare the files. Especially when they are shot with different camera settings / lighting conditions, but you have to make them look similar.

Lightroom has this feature for ages, but as a retoucher I have small series & process them in ACR.

(the screenshot is from a Youtube tutorial)