They’re upgrading this to require you to write “mobile deposit for XYZ bank” as well, so that you can’t double-deposit without getting caught early on.

I mean, whats the point of signing the back of a check? Most businesses don't sign the backs of their checks. They use a stamp that has their business name printed in some ordinary font. At that point you might as well let the mobile app superimpose its own signature or have the ATM apply its own stamp.

My bank upgraded their branch ATMs to accept multiple checks at the same time for deposits. What surprised me was the displayed instructions said one did not need to sign the backs.