High betas, twins?

I had ivf for secondary infertility. They did pgt testing for gentically normal embryo, icsi and assisted hatching and I was told it was a slight increased risk of egg splitting and twins but only one embryo transferred. I had my betas

First 10dp5dt: 1268

Second 12dp5dt: 4062

Third 17dp5dt: 20,130

They seem really high.

They won’t do an ultrasound sooner, scheduled January 11th.

If you had twins what were your numbers?