[souffle]

Hi there - it does sound like Murphy may be female as that is definitely the position a female adopts when standing and in heat.
What species are they? If they are Syrian (I assume not) the should be kept strictly alone. If they are dwarf species then obviously if you have a male and a female these need separated as well. Sometimes youngsters can get a little confused as they mature. You need to check them out carefully. Only females have nipple lines so if you see nipples then it is a female. Next check the two vents. A male will have a gap between the two vents usually with fur in it. Male dwarf hamsters also have a much more prominent scent gland on the tummy and this can be stained yellowish. In a female the vents are very close together and you don't see the bulge of the testicles. Even if you cant see the testicles you can usually feel them. Can you post some pics?