I have a dog whose owner died and his mother could no longer take care of her, she told me that the dog has had her rabies shot last year and would send me the paper work so I can get her tags, but so far no paper work. I have to have her spay and get tags to do so I need to prove she has had the shots, so will it hurt her to have her given a second shot

1. Merely ask them what vet the dog used, and get the records there.
2. this is a question, you need to ask the vet, when you take him in.

You can ask the vet to run a titer test since you don't have proof of a prior rabies vaccine.

Getting the rabies vaccine twice in a year is just fine. The vaccine is safe (although, with all vaccines, there is a risk of reaction). The vaccine is actually given in a booster series when pets are exposed to rabies positive animals. Plus, it's not like the vaccine is being given back to back.

Speak with YOUR vet and see what the best plan of action is.