It wasn't wrong from the get go. It was to code when the house was built. Things change. I had to add GFI to my kitchen and bath to sell my old house. They left alone my 2-prong outlets. Are wired with ROMEX or with the two wires inside a metal cable? All the outlets in my old house were two prong. I think they ran the ground via the metal cable. We always had to use those 3-prong adapter things with the eyelet to the cover plate screw. If it was legal when it was installed, it might be legal to extend it. How many people with houses built in 1957 are rewiring their houses? I've never heard of many. Maybe this is a common thing? I don't know. It can't be cheap. The best compromise may be to add a new run from the breaker box. If your house is like my old one, you are at full capacity at your breaker box. So you need a breaker box add-on.