My vet's schedule is that that pups must have two puppy shots after the age of 10 weeks. I start my pups at a little over 7 weeks so there is only a series of three shots that way.
He would give the rabies shot with the last puppy shot if I let him. I wait until at least 6 months of age... usually older... my Rambo was 8 months old and my Emma was 9 months old when they got their rabies shots. They never went outside before then.
My Winnie was recently spayed and she was due her 3yr rabies shot... they wanted to give it to her after her spaying. I nicely declined that offer.
I never let the vet give more than one shot at a time regardless of the age of my dogs. If any reaction occurred I wouldn't know which shot caused it.