For tax purposes, if I receive a check with unacceptable conditions attached, is that income?

I signed a contract agreeing that I would be a 1099-MISC independent contractor. I am not sure if I legally met the definition of a 1099-MISC independent contractor or was actually an employee. In any case, the last two checks that were given to me (I was entitled to them and have not yet signed them) say "In full and complete settlement of all claims past, present & future and by signing above you accept these terms" and "In full and complete settlement of all claims past, present and future and by signing above you accept these terms". Is this "receipt of a good check" which constitutes taxable income when delivered, even if I do not cash the checks until later? If I am unwilling to sign these checks because of the terms that the payer wrote on them before sending them to me, and I therefore cannot cash them, am I still obligated to pay tax on them?