If you wish to work, For example, From video, The permission 1920×1080 create the project, The permission 1920×2160 (over / under) or 3840×1080 (side-by-side). Import the tracks in the project and drag them on the timeline. The kspp itself will define a kind of a stereo of pair.
Select the left and right track in the timeline, Click the right button mouse and choose "nest" in the context menu. Work with new sequension as whit one track.
Also can use the filter "convergence".