Complex sentence: Fred and Mile are two boys who very much resemble "Quick & Flupke", another of Hergé's creations; in fact, the final frame in the double page gag is almost identical to the final frame in the Quick & Flupke gag "Unbreakable".
Split into simpler sentences: Fred and Mile are two boys who very closely resemble the protagonists of Hergé's "Quick & Flupke" series. The final frame of "Fred and Mile" is almost identical to the final frame in the Quick & Flupke gag "Unbreakable".