No, it's not. The embryo Feng talked about was Yiyi's, which he stored since he used his sperm instead of Yiyi's to make Rourou.
So, it's not that he used 2 sperms to make Rourou (which something that impossible to do), instead, he used Yiyi's on the different egg and produce different embryo. That embryo got stolen before by, probably, his aunt. And the baby shown before is, probably, Yiyi's real child.
An embryo is created from a sperm and egg. Jinyao couldn't add another embryo to an embryo that was already created from his sperm and a woman's egg. It's impossible. So no clearly the embryo Jinyao was talking about was the one that was created from Yi's sperm and a woman's egg which he had replaced with his own embryo that ended up being RouRou. The aunt however got ahold of Yi's embryo instead, which I'm pretty sure neither Yi nor Jinyao are aware of yet. But that's the one Jinyao was telling him about, clearly.
Ahhhhhh omg my excitement rourou is BOTH their child @hhhhhhhhhhhhhhh