No, the masculine plural form of "banal" is "banals".

.....except in the very rare case when the adjective "banal" us used in its other meaning: feudal (as in the "feudal system"). In that case the plural masculin is "banaux": "les moulins banaux" = the feudal mills where peasants could mill their grain paying a fraction of it to the lord of the land.

-- Chris (not a native speaker).