Here we go again, guesswork and speculation. Make it up as we go along….
Thomas Rouse was a DC promotor, it's widely accepted that Fairmount came first (Beverly had already had a record on Fairmount before this (She kissed me), Rouser came second, but there probably wasn't a great time difference between the two. I'd say less than a year.
Whether the Rouser issue was licensed or not - we don't know and maybe someone should ask Frankie Beverly before his memory goes. There may well be a logical explanation for a local or second issue on Rouser in DC.
As for the El Corols Rouser release being a bootleg - that record was about a year later than "Because of my heart" (Jan 67 for Frankie Beverly). Tiny Records was the label of one of the band members Tiny Barge, again there may have been an agreement for Rouser too also press it up.
My tuppence worth, we just don't know for sure (yet!) so lets not make it up guys (and gals).