I had that same glitch happen to me. I'm pretty sure that she didn't have twins to start (I was able to check an old saved game...), but one might have been lost to a starvation situation.

She would carry two of everything, I've attached some images I saved at the time. (Of her honoring the dead and making a stew.)

At one point I saved the game and then did some experiments on what happened after she had kids. I tested with twins and triplets (she was very fertile!) but after she stopped caring for her babies, she reverted back to to carrying only one item.

I reverted back to my saved game and just let her continue carrying two of everything. Alas, she died a while ago.