sportclimber Yes, there is. You'll find it on the website and in the DeoVR app next to the JAV and compilation toggles. In DeoVR it replaced the old flat toogle, and it seems the old flat collection is gone from the app.
I think there are about 30 videos so far. It's not easy to tell though. Switching on the new flat toggle will mix those videos into the regular VR feed, so it's hard to find them. You could search them by tags (flat, immersive flat, stereo AI (3d)) but it seems some videos have not been tagged correctly.
Right now you have to switch off 'force mono projection' for each of those videos in DeoVR if you want to watch it in 3D flat.