I don't see what giving 2 shots a month apart would do AT ALL. You might want to call them and ask if this is the norm.
For initial vaccinations, we give a course of two shots 2 weeks apart. After that, its just one yearly booster, 12 months after the initial vaccination.
Vacinations CAN cause symptoms of the disease they are vaccinating against, although it is rare. After all, a vaccination is developed to make the immune system develop antibodies against that particular disease. If an immuno-supressed animal (or one just under the weather) is vaccinated, and the body does not develop the sufficient antibodies, then symptoms will show.
Both my dogs developed kennel cough after a KC vaccination. Needless to say, I've never vaccinated against that again. My flu carrier cat shows flu symptoms after every vaccination. Even vaccinated dogs can get parvo.