Extreme HCG rise?

Hey ladies so I got my first blood results (24/7/19) my HCG level was 39 so the doc told me to retest, I did do on the (26/7/19) at the exact same time and my HCG was 100+ ?!

I was just wondering if it is normal as I have looked around and it is said to double however mine has more than doubled.

Any answers would be greatly appreciated! xx