The 12" Collection is a compilation album by British rock band Queen. It features various 12-inch single format recordings and remixes. "Bohemian Rhapsody" was never released on a 12-inch single and the sleeve notes state that it is included due to its length.

"The Show Must Go On" did appear on a 12-inch single. However it was not extended and appears on this album in the same format as before. The sleeve notes do not mention why it was included.

...
Wikipedia