[mountainboy]

umm, no. just no.

fungibility means that two units are interchangeable/equivalent. Legality doesn't enter into it.

anything that makes unit A perceptibly different from unit B can cause humans to value unit A more less than B.

Some units may be perceived as "better" than average and carry a premium. Others may be perceived as "bad" or "tainted" and trade at a discount.

Such differences are generally considered undesirable in a money.