BTDT Moms....Finding out the sex

I have a 16 and 20 week sonogram scheduled. As i am carrying identicals i they will be the same sex. Is there a chance the doctor won't be able to tell at either one??

I want my husband to be at the 20 week one to find out with me, but if the doctor knows at the 16 week one i might beg him to tell me.

Just wondering what your experiences were.

I'm worried I'll cave in and find out before my DH also. I have a 17 week scheduled for Tuesday which my DH can't attend. My 20 week isn't until April 12th. I am scared I will give in to temptation and find out what we are having without him.

There were not able to tell at the sonogram I ahd at 16 weeks, but they could see only one of them at 18 weeks. We had idenitcal, but at first there were not sure.