This from a 2006 CD release "The Marathons & Friends": "The story goes that Barnum had come up with the idea for “Peanut Butter” and had earmarked it as a possible single for The Olympics, but they were on tour and he was so enthused by the idea that he and Arvee Records’ boss Richard Vaughan determined to press ahead and use a “session group”. Their mistake was to use The Vibrations in toto, rather than less well-known voices.
So who recorded the tracks on the follow-up singles, “Tight Sweater” c/w “C. Percy Mercy Of Scotland Yard” (Arvee 5038), “Chicken Spaceman” c/w “You Bug Me Baby” (Arvee 5048) and the rest of the tracks on the LP ? Joel Whitburn attests it was just a bunch of Los Angeles unknowns. Certainly no-one has ever suggested it was The Olympics that were persuaded to record the tracks (their producers Fred Smith and Cliff Goldsmith share composer credits on “Peanut Butter” but were not involved in any of the other songs). Well, finally we can reveal all. “Chicken Space Man” and “You Bug Me Baby” were Barnum and Cooper duets and the rest of the tracks on the LP (“Talkin’ Trash” wasn’t included) feature the voices of Bobby Maccagnanno, James Hall, Freddie Sachel and Art Wheeler".
The Marathons were really The Vibrations - "Peanut Butter" was recorded for Arvee while the Vibrations were still contracted to Checker. When the Arvee single started selling Chess sued Arvee. The resulting court judgement:
1. Assigned the master of "Peanut Butter" to Chess/Checker who promptly issued it on their Argo subsidiary crediting the single as by The Marathons so as not to confuse radio stations etc.
2. Allowed Arvee to keep the name "The Marathons" - the label then put together a new group who did a few followup singles before disappearing. I'm not sure if the lineup of the second Marathons group has ever been uncovered.
Final mystery - the Arvee b-side "Talkin' Trash" was replaced by "Down In New Orleans" when Argo issued their single from which I'd infer that the rights to "Trash" didn't go to Argo in the court settlement so Argo had to put something else on their B-side. This opens up the possibility that "Talkin' Trash" isn't by the Vibrations/Marathons but some other group whose real identity is lost in the mists of time.