Echo in guests mic

Hi guys me and the wife have started a duel podcast. The problem is when we record together I can hear an echo when I talk but not when she talks. I'm using an at2020 and she is using a rode ntusb. I've tried turning it down to stop the mics picking up the background sound and put up a blanket behind where she sits to help it. It's helped but the echo is still there. We sit maybe 7-8 feet apart facing each other. When I record by myself there is no echo on either of the mics.