Look at the beaks
If they are the same tone and the end has the same colour you most likely have the same sex
Each set of birds are different per breed
My Pekin / khaki babies my boys have a black end but orange / green bills
My girls have lighter ends but darker bills
My blue Swedish have dark bills and dark ends one is starting to quack but I’m sure they are both girls as the beaks are the same at 5 weeks