Anyone pregnant having their levels increase more than half in less than a week?

Currently my wife is 6 weeks and 4 days pregnant on the 20th we went in for bloodwork at 5 weeks 5 days it stated hcg was 4835 we went back yesterday and levels went to 24000. Not sure if it's multiple but her grandmother has 4 sets of twins and no one else in her family has twins. Waiting for the doctor to call back for date on ultrasound but for now it's crazy to think two babies when we expected one lol