Friends of ours have their DD christened catholic.
They weren't married & she wasn't catholic. The 2 god parents they chose weren't cetholic either, so they had an extra god father who was catholic. So their DD has 1 God mother & 2 God fathers (DH is one).

It is actually costomary as far as I know just to have one of each. My brother, sister & I were all christened catholic & have one of each.

Mum & dad had issues getting us christened as they were married in a garden rather than the catholic church, so the curch didn't view them as married & refused to do it.
The only reason we were don is coz there was a fill in preist with me & my brother was inly done coz I was.
When it came to my sister, the church wanted mum & dad to re marry in the church. They refused to do it til mum & dad were married in the eyes of the church.
Eventually though it was all ok & when my sister was one they finally agreed.

All churches IME have different policies. Its up to that particular church & that preist how things are done. My bro sis & I were done 25, 23, & 19 years ago, so most of them are alot more relaxed about it these days.

I always wanted to have my kids christened, but my DH doesn't have any beleifs & didn't want to do it. He did agree to us marrying in the catholic church though.