Well I've just been searching for any information I can find about it but nothing that actually says it can be mixed but I did find two different meds called, DUOTONE FORT and PHENOKINON F, that both have progesterone and estradiol in them... Maybe there is some truth to the claim??
I'll keep looking if I find any information supporting or disproving it I'll post it, but at the moment I'm thinking mixing is a really bad idea.