What gender are my babies???

Lina

So I went to a 3D ultrasound place at 16 weeks for my twins and they said baby A was a Boy and baby B was a girl. Then I went to my 20 week ultrasound and she said both are boys. Then at the end of the appointment she checked baby A again and she said she thinks it’s a girl. If she’s right then the 3D place was wrong with both genders! Now I’m just confused

Has anyone ever had an uncertain 20 week ultrasound?