Labor happened Twice. One of the babies isn't even related to the family.

Issue

I have a second baby from a pregnancy on my lot, named as I chose to name my sim's child but not resembling either parents and not part of their family tree. 

Steps you took for Issue to occur

This is my first game in the Sims 4. A young adult sim was pregnant, went into labor, and then during labor got an invitation to another lot for a birthday party. I clicked accept (mostly thinking "yeah, that's hilarious, two birthdays in one!")

The sim went to the party, and went through labor at the party. Then when it was time for the delivery, she disappeared off the lot and the text box popped up saying something like, she had the baby at the hospital, "It's a boy!", asked to name it (which I did), and then another dialogue box popped up and asked if I wanted to return with the baby to my home lot, or have the sim return to the party lot. I decided she just had a baby and best to send her home. 

When she got home there was a bassinet pre-generated on the lot with the baby in it, named as I'd named it. But it didn't look like either parent (one parent was blue, the other black, the baby is white) and my adult Sim was still pregnant, and just at the start of labor. 

She completed labor, had another baby, also a boy, but this one was blue and looked like his parents. I named it. Then went to feed the first baby, and couldn't breast feed. I checked the relationships and family tree, and she and this first baby are not related. 

Picture

Mods/CC

No mods. Just got the game.

Expansion Packs/Game Packs/Stuff Packs

No expansion packs.

Occurring since

Game was up to date as of yesterday when this occurred.

Operating system

Mac OS 10.11.5