I live in Pennsylvania. My girlfriend and I used a sperm donor for her to get pregnant. Can we both be listed on the birth certificate without going through adoption?

Have you tried contacted the office that deals with this matter and ask? I not 100% percent but you might be able since they do let same sex couple adopt. Call to find out.

No, on the birth certificate it would be fraud to list someone as the
"father" who is not the father, this will have to be done though adoption after the birth