Same operands in AND expression after simplification

[tomas789]

When simplifying the expression

AND(TRUE, OR(OR(symbol("x0"), FALSE), AND(symbol("x2"), TRUE), NOT(TRUE)), AND(AND(TRUE, TRUE, symbol("x2"), TRUE), NOT(symbol("x0"))))

Which produces the expression

AND(NOT(Symbol('x0')), Symbol('x2'), Symbol('x2'))

Which could be trivially simplified to

AND(NOT(Symbol('x0')), Symbol('x2'))

[tomas789]

I can confirm that the PR https://github.com/bastikr/boolean.py/pull/113 also fixes this issue.