Yes, you can mate together the two different cable size contacts. Both male contacts and both female contacts have the same front half of the contact for mating compatibility. It is only the bore at the rear of the contact, where the wire is inserted, that is different for the 26 AWG and 28-32 AWG types. So both female contacts G125-0010005 and G125-002005 mate with both male contacts G125-1010005 and G125-1020005.