There was an informative
2008 thread on the topic of T204's. Peter Thomas proposed a theory that the 6 players with square border cards were also issued with blank backs at the same time as a type of A/B test for Ramly. We don't know if that's the case, but it's plausible.
I'd be skeptical that any blank back of a player other than the known 6 isn't skinned. There was a
Freeman card in a 2014 LOTG auction that's an example of this (SGC graded it, but probably shouldn't have).
Those 6 players (Anderson, Bancroft, Bransfield, Burkett, Dinneen, Moran) are also the easiest 'normal' Ramlys to find, btw.
Bill