So there was this movie about a guy that tries to find some books that would lead him eventually to a big secret, but there are only 2 copies of those books in the whole world. I think it's released in 2006 or something.

That sounds like a very simplified version of the plot for The Ninth Gate: The Ninth Gate (1999) - IMDb

If you saw it on tv, could it be older than you thought?

If you saw it in a theater, do you remember any other bits about the plot or actors?