Vets, pet stores and/or adoption kennels are required to give you a copy of your pet's rabies certificate. If one can't be found, have your pet vaccinated again, just in case. (A vet can confirm how long between vaccinations is safe for the animal.)
For you to know which rabies shot they received, it is always recommended to discuss it with your health-care provider. It is not good to receive the vaccine if you have ever had an allergic reaction to rabies vaccine.