Is it possible to have more than one personality disorder?

It is possible to have more than one at once, but those tests are VERY unreliable. They don't even serve a real purpose. They're based on the general symptoms, and if the test takes all the traits from any given person's personality, it's going to come up with a positive for quite a few. Don't listen to the test. Besides, a person who really does have a PD doesn't even consider the fact that they do. They always get diagnosed with it because they went to a therapist for something totally unrelated and it popped up, or a concerned friend or family member made them go.