Ouch.
Either way be fairly confident they share the same plot:
Remarks in the register, seem similar, as I read them:
Frederick Barstow 1946: 9 Row Low side 18 f(rom?) near side
Millicent Barstow 1948: 9 Row L(ow?) S(ide) 18 f(rom?) near side
If you look at our Burial Records over to the left and there you will notice that one of the headers says "MAPS".
Look for the one for City Road.
Left hand side of the page you will see there is a section for "U" and one also for "U1. That is probably why the error was made by the recording clerk at City Road. There are two sections of "U's" as I noted above.
Sooooo husband and wife are probably in the same grave in U1.