I am using 2 Olympus SP500 cameras with Sebectec software. Both cams are mounted on remote pan/tilt heads so I can point at different targets. Right now I have them aligned so I can stitch the two images into a panorama. The native time lapse video is created as an .mp4 file with the Sebectec software. This is done at 30fps. Then I use Sony Vegas to put the "finishing" touches on it. I can stretch or shrink the timeline to get the playback speed to where I want it. This also seems to smooth the video a bit, since it is rendered at least 2 times. For the panorama time lapses I take each time lapse file and put them on adjacent tracks. I adjust the left image -480 pixels (half of half of 1920) on the x axis and set the y pixels to 540 (half of 1080). I do the same on the right image only +480 on the x axis. Then I stretch the timeline to align both tracks. This will create a side by side video. I save that file and then open it up as a single video file that I edit further. It sounds a lot more complicated than it really is....
Greg