Brazillian ABNT2 keyboards provides a comma and a dot key on the numeric keypad. The dot key has evdev keycode 129 and the comma key evdev keycode 91. If I understand correctly, the rules file adds +inet(evdev) to the symbols of that keyboard but inet(evdev) sets key I129 to symbol KP_Separator, overriding the previous br setting of KP_Decimal. This combination makes both keys output a comma. Removing the line key <I129> { [KP_Separator] } from the evdev section of /usr/X11/xkb/symbols/inet makes those keys behave correctly.
After discussion on IRC, I am changing I129 to KP_Decimal in symbols/inet. Please check in git
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