I guess it begs the question: “What is the purpose of a Birth Certificate?”
Why list the parents at all?
If the baby is from artificial insemination from a sperm bank, thats pretty anonymous already AND you really can’t presume that donor as the “father” for legal purposes, tho some have tried.
Having 2 women or 2 men as the parents is meaningless in so far as it is not true, biologically speaking.
MAYbe it assigns a second responsible adult for the state to chase down when the relationship invariably fails.
Its a sad sad mess that these poor kids did not ask for.