How can I know if a music is in module format just by listening to it?

[Metro28]

How can I know if a music is in module format just by listening to it?

[Saga Musix]

Simply put, you can't, just like you cannot easily identify whether a song was made using a hardware sequencer or a 4-track tape recorder. You can guess, though.
Many modules use the same old, low-quality samples, and while it is of course absolutely possible that the same samples would be used by someone outside a tracker, it's often an obvious hint. In the end, this is just an exercise of actively listening to lots of module music - you will then learn to identify those samples. But the newer the modules become, the harder it will typically be to guess if they were made with a tracker or not, because a tracker can provide the exact same fidelity as any other audio tool. There may still be some hints in the way instruments are played (static-sounding samples, no round-robin, arpeggios, tracker-style portamentos...) but at this point it's essentially guesswork.

[LDAsh]

Just like all the PlayStation games that essentially turned a MIDI file into a WAV on a CD.  Some of them, like Dark Forces, even just screencapped the DOS version and turned that stuff into MPEGs.  Especially with software like OpenMPT, it can do a LOT more than just Amiga tracker chiptune files.  Many people would tell me that I'm barking up the wrong tree by attempting to use it at such complex and high-end production standards, but, I've already proven to myself that it's very capable of that.  It can swap samples in and out very easily now, and we just disable some channels and essentially it does become a ye olde tracker file anyway.  Who would ever know?