When people say a baby looks like someone famous, or that he/she resembles a parent, they're usually just saying so to be polite, because most babies look like babies or, in this case, like Cabbage Patch Dolls.
In fact, we should just start telling people their babies look like a certain brands of dolls, because the resemblance is remarkable.
Since the proud parents are likely to get upset if you say the baby looks like a toy rather than either one of them maybe you should just stick to saying "your baby is a real doll".
And if you do compare their offspring to a doll just be careful which doll you compare them to!