Part of the problem of working this out is the ease with which doors can be changed. I have several backs but only one body so I don't really know which was the original one with that back.
I went through my Pentax bodies.
Early Spotmatic: no roller.
ES, ESII, KM, KX and K2DMD has a roller.
ME Super, MV, MG, MX, Super A, Program A: no roller.
It appears, therefore, to be something Pentax did between (roughly) the era of the Spot F/ES/ESII and the original K-series, but dropped when the M-series came in. The odd-one-out is the LX which doesn't get introduced until 1980, but appears to have a mixture of backs with and without a roller.
Confused... you soon will be.
K.