This is very interesting. In some cases there are books that some user recommended and then the book listed is not that one. As an example, lots of people are

This is very interesting. In some cases there are books that some user recommended and then the book listed is not that one. As an example, lots of people are recommending Spivak's "Calculus", or "Calculus Made Easy", from some other author, but the one listed is "Calculus" from James Stewart. Same happens for the book "Calculus: Early Transcendentals". Sun Tzu's Art of War is also repeated with two different editions.