I cover scanned a 1967 FF paperback I got recently.
I got 2 choices that are just 2 different names for the same 50 cent 1967 Lancer paperback, just slightly different coloring, which can be accounted for with fading on one over the decades.
Title page says “The Fantastic Four Return”
Similarly, the following book from 1966 is also in under 2 names. The title page just says “The Fantastic Four”:
The Marvel collector’s album series appears to be a catch-all for the various Lancer paperbacks published in 1966-67, while the duplicates are each of the books given their own titles.