Making another attempt to like Sims 4 and I seem to have found an odd bug.
My sim became pregnant with "try for baby" option and went through a normal pregnancy and gave birth. The birth was at home and allowed to occur in its own time rather than forced to give birth by a bascinet or hospital visit. She gave birth to a girl and I named her. The ribbons on the bascinet turned pink and the bascinet teleported to the mother's bedroom (I don't recall this happening when I played sims 4 before). Both parents had the new baby buff.
I let the mother go to bed as she was exhausted and noticed the next morning that she still looked heavily pregnant. Then I saw she still had the third trimester buff. A little later she had the going into labour buff and gave birth to another daughter (about 24 hours later). This time, after I'd named the baby, the ribbons on the bascinet stayed yellow and no teleportation happened. Confused, I looked in the family tree and my sim is listed as only having one daughter (the second one).
The mother hadn't travelled at all since becoming pregnant and noone hed left the house between the birth of first and second daughter. I'm also not using anything other than the base game; no expansions and no script mods or custom content. I'm rather perplexed and have no idea what to do here. I don't mind if she has one baby or two really (I'd prefer one), but I don't really want an extra sim in the house that isn't related to anyone.