Combine multiple videos as separate streams in one mkv file
Yes, this is possible using ffmpeg and the mkv container.

An example command sequence would be:

ffmpeg -i input1 -i input2 -c copy -map 0 -map 1 output.mkv


source

Breaking down the command:


-i input1 This selects the first input file. Could be something like my video_track1.mov.
-i input2 Here you can specify the second input file. You can add another entry -i input3 if you have more input videos. I don't know what the maximum amount of videos is you can place in one mkv container.
-c copy This copies all the streams (audio and video) in their original encoding.
-map 0 This maps all the streams (audio and video) of the first input file to the first track of the output file.
-map 1 This maps all the streams (audio and video) of the second input file to the second track of the output file.


More information on the -map option can be found in the documentation of ffmpeg.