Is it safe to run and old photo through an inkjet printer? Has anyone done it?

Assuming the old photo you have is a print that's 30+ years old, then the paper will not have an inkjet receptive coating and the inks will most likely run. You might want to scan your old photo, print onto a fiber inkjet paper (such as Moab's Juniper Baryta Rag) and then do your double print or embellish.

Thanks. The prints were made on fiber-based paper, not resin coated. I'm specifically looking for a way to repurpose the old prints.