Red and blue integers: there is red 1, red 2, ... 0, blue 1, blue 2, ... . Addition and subtraction as you expect. There is no ordering, also no multiplicative structure. There are 2 isomorphism into the additive structure of the integers. (Red and blue reals are defined similarly.)

I find this structure to model charge better. If not for else, at least it prevents you to ask silly questions about charge.