What Could Be The Extra Circle In The Uterus?

I went for a 3D ultrasound yesterday to see perhaps why I have been have reoccurring miscarriages. My fertility specialist said she saw two circles that only should have been one on my upper uterus. She said she had to look at the ultrasound pictures to confirm but that she thought I may have a septum on my uterus. However, I had ovarian drilling less than a year ago and my OB said my uterus was perfect and normal. I was told you are born with a septum if you have one. If it s not a septum, what could the extra circle be and could it be aiding in my infertility?