The reference is from the gro index of marriages (wherever they were held, parish, non conformist etc)
The things you are referring to , generally, are transcripts.
That is why I suggested you look at originals! Like the marriage cert. Yes, she may have only "made a mark", but you wont know till you look at it. And you can see how the vicar AT THE TIME spelt the name (OK only his idea of how it was spelt, but he would have heard the name said, and Frener and Freuer would sound very different). Much better than either the index (relying on the indexers reading of the vicars writing) or Ancestryes index of that index, relyoing on their transcribers interperatation of the gro indexers interperatation of the vicars writing!
Likewise Rebbies birth cert - how is her name written on her birth cert? (Not a census, or an index or transcript), but how did the Registrar write it AT THE TIME, when her mum or Dad had just said it?
Do you see what I mean?