How early did you find out about twins

Kelli • My wife and I got married in March 2015. We had our first baby together may 25 2016. We are trying for baby number 3!
My wife and I want twins. We had our first ultrasound, she said just one baby. But a coworker of my wife said she didn't find out til the second scan bc one baby was high. So her first ultrasound said one baby too. Anyone have this happen ?