Positive for Pregnancy

What are the odds of getting two false positives. I can’t go to the OBGYN to confirm until Sep. 11 and it’s driving me crazy! I took two different one from different stores. Both Clearblue, I took one at night and the other the next morning and they were both positive. So do false positives happen? Also, I read too much on the internet too much and it says that some cancers produce Hcg which causes a positive pregnancy test. Needless to say, I’m freaked out. I’m ten days late and I have two positive pregnancy tests and I’m about to scream.