Progenity results question

Is it me or I’m I overthinking -

I haven’t had a ultrasound since we got a positive test at 3 weeks and ultrasound issued at 6 weeks measured at 8 weeks.

Got the Progenity test results and it says I’m having a girl. We are excited but the tests says XX AND XY? Has anyone ever heard of this?

Because my intuition has been saying from day one I was having twins. I’m measuring at 16 weeks and just turned 15 yesterday but I’m HUGE!!!

Thoughts ? Can a xy chromosome be present in a girl fetus?