urrggh, this seems to be an SDL bug; it thinks both keys are physical capslock remapped to escape.
that's a little bit out of my hands (though i'll look for another key to use as an emergency menu key), but i found a very strange workaround: if you turn off caps:swapescape, start the game, and then turn swapescape back on, the physical escape key continues to work
(i assume you think capslock should function as escape in the game as well? i'm never sure when i should check key mappings and when i should check physical scancodes)