fireman sam - are you just two people booking ?
If so, then there should be no problem with an extra two in the other bedroom....except.... there may be hotel/apt laws that require each persons name to be registered for local police or fire regulations, though i doubt these are rarely enforced if they exist at all.
Your question is slightly different from the one posed in the thread previously quoted where Hillsalt wished to accommodate extra people in one hotel room. Your accommodation seems to have ample space for four -go for it.