Double session CPT® code?

First, I'm new to here and this is my first post so thank you in advanced. I'm not trained in medical billing so this is really strange to me.

We have a patient (psychologist's office) who came for multiple double sessions. A single session lasts 45 minutes, so her sessions were 1h30m. I have no idea how to code for that. We usually use 90834 so this is throwing me for a loop. A response is greatly appreciated since her claim for Aetna will be denied based on the wrong code.