Hi Jeff,
I'm looking at the BSA Twin Restoration book and there is a clear photograph of a 1947 A7 with a hinged rear guard on page 11.
On page 148 it describes the rear mudguards for the A7 and A10 models and the changes that were made to them. It states that the first (1947) A7 had a rear mudguard with the tail able to hinge up. In 1949, this was joined by another, still with a hinge, for the plunger framed models. The rigid mudguard went in 1951 and the plunger type changed in 1953 when a boxed in number plate was fitted but the hinge was retained. They continued in this form up to 1957 when the plunger model was discontinued.
So, Jeff, I reckon we have to treat the restoration book as "Gospel" which means that neither of your fenders were originally for your bike. Have you tried fitting either of these to the bike yet, together with the support stays? If so, are they a good fit and do they look right? If the answer to both of these questions is "Yes", I wouldn't worry about it too much. If the answer is "Yes" and you want the bike to be authentic, you could always cut one of them and fit a hinge!!
The A10 picture on the home page is a good guide.
Good luck with the restoration.
Beezageezauk.