[Nicolai P. Zwar]

I don’t really understand the question. Isn’t it perfectly normal that if one hears a piece of music one likes in a trailer, one may wonder what that is and where it originally came from? It used to be that they often used music from one movie in the trailer for another. I guess nowadays, trailers even oft have “original” music composed for them. And there are even soundtrack CDs/digital releases just with trailer music.

There used to be a list on Soundtrack net back in the day with lots of information which music was used where. Not sure if they moved to filmmusic.com, which is where I see the list now: Trailer Music list on Filmmusic com

It has a list of “Top frequently used cues”, with ALIENS, for example, listed 24 times.

I used to sometimes wonder which music I heard in a film trailer, and these sites often helped me to find that information.