One or two apostrophes for two subjects in the possessive case?

Which is correct: [Bonus question: should there be a question mark here instead of a colon?]

The book contains Marx and Engels' theories about the nature of
society and politics.

or

The book contains Marx's and Engels' theories about the nature of
society and politics

It seems to me that the former is more common, but I am confused here since the latter seems more logical to me (and matches what you would see in my native language Icelandic).