We recommend you to merge different video files and convert them into one file before registering. You can do this with Codimg programs: In main menu, tab "Tools" you will be able to merge only the video files, or merge the files and their corresponding analysis..
Alternatively, you could analyse each file separately then add registers from each timeline into a Presentation window. This workflow is possible from Codimg Advanced as it allows you to work with up to five videos in timeline and presentations. Codimg Premium allow you to work with unlimited videos in these environments.