Um... Sadly, yes, but I do not know if it is a mistake. A loooonnng time ago (and I just remembered this now) I had a V4 and V4.5, both girls, both good friends, and both old enough to get married. I had an item on the V4.5 called the Honey Love Potion and gave it to my Tamagotchi and she blushed and there were hearts everywhere. Then I connected her to my V4.5, and alas, they had babies. O_________O I wish I could forget that again.
Also on earlier Versions characters can be either gender so you can make Memetchi marry Violetchi and stuff like that.