Hi Liddicoat,
A bit confusing, Caroline may have been married before, though not found any evidence yet. Why fathers name Gwyilm/Edwin I dont know, maybe an error on one of the certificates which does happen. I've got one where the fathers name on the marriage certificate is Henry but the birth certificate says Thomas infact I've got another one which says Thomas and the fathers name is Charles
The marriage in 1855 for Caroline Joanna Giddy perhaps going for that certificate. What I would do is to apply to the local registry office for that area, with an explanation, not to sure the cost normally certificates are £7.00 but they may have a postal charge. If the groom isnt the one, think you may either get a full refund or partial. Hope this helps.