My signature on a touchpad is noticeably different from my paper signature. It’s been a real challenge for me recently as I’ve had to sign a number of paper documents while the “official” signature on file for me is an electronic one from a touch interface. A few times I have had to resubmit fresh copies when the first ones were rejected.

You could also claim it wasn't your signature and be refunded, but you can't claim that if the delivery person obtained the password only you had.