"Double taxation" is absolutely constitutional. Tons of things are double, triple, quadruple and more taxed.

I make a W2 salary. I pay federal income taxes on it. I pay FICA taxes on it. My employer pays payroll taxes on it. I might pay state income taxes on it. One event, tons of taxes. I take that quadruple taxed money and buy a dinner with a beer. Sales taxes on the overall sale, additional taxes on the alcohol, additional sales tax riders because I bought it in the touristy night life area. Triple taxes on my quadruple taxes, good lord! Unconstitutional!

Worthless phrase, "double taxation".