These were (I assume monthly) bound-together remaindered copies of selected DC and Marvel comics with covers taken from original DC comics or sometimes new covers adapted from interior scenes. Very hard to find in Near Mint but often show up on eBay UK in low and mid grade. Good reading value. #1 of this title seems to be scarce for some reason.
To my knowledge there are 24 different Double Double Comics across a number of titles - Action, Adventure, Batman, Detective, Jimmy Olsen, Justice League, Lois Lane, Strange Adventures, Superboy, Superman and World's Finest. But I'm still looking! This was the first Double Double Comics title from this publisher and the only one to reach 4 issues.
This particular copy as illustrated has Action Comics #340 (1st appearance of Parasite), Action Comics #346, Action Comics #348, Showcase #67 (1st B'wana Beast).
Nov 2023: I sold another copy on eBay with the same contents So I wonder if the early Double Doubles all had the same remaindercomics and later copies had more variation of content?
Note: some PR issues may have no value. Selected issues in FN, VF or VF/NM may not exist in some titles.