contrary to popular belief both sexes have spines on their gill plates
however those on the male are longer and therefore visible to the naked eye (just).
Males tend to have a rough patch of scales at the base of their caudal peduncle,
again this is often hard to detect in younger fish.
My M/F pair look almost identical now but the females caudal fin is defiantly bigger than the males
(which is why I'm thinking you do have a M/F pair)
and the male is larger than her in all other dimensions (length, height, girth etc)
but when they were younger they were of equal size.
I think the next 6 months will tell for sure if you truly do have a M/F pair or not.
look for signs of 'him' pushing her sideways with an open mouth and her
shimmying in front of him (much like a female krib does),
of course if you see a bubble nest then you most certainly do have a true pair.
I wouldn't keep them separated for too long as this could lead to territorial issues when you reintroduce them.
even if they are not a true pair they will happily co-exist provided they are brought up together.