Not sure what you're asking. Do you mean you're connecting the recorder to the camera and want to know if you get both the camera audio track and the Tascam audio track? Or just one of them?
I guess look in the menu of your specific camera model about it (not sure you mean an actual video camera, or a camcorder or DSLR which can also do video).
I imagine if you're connecting any mic, or a Tascam recorder, it should record it directly to the video, and you would only do this if it's better than the built-in mic, and it should be synced just the same.
Why would you need the built-in mic audio? The only reason I think is to sync but that's only if the mic/recorder is not connected directly to the camera... no?