If you were not a "union RN" and did not otherwise have a written employment contract defining the criteria for and handling of bonuses, this would be perfectly legal: without a contract, bonuses are discretionary; being discretionary, they may be given or not at will, without explanation; if you were given a bonus week 1, but the company decided that you should not have received it, then if you otherwise might have received a bonus in week 2, the company could chose to not give it to you, to balance the scales; and they would not need to document the "canceling out" in any way on a paycheck or -stub. You would have no right to get the bonus you feel you should have gotten, since you would have no enforceable rights to discretionary bonsues.But since you are in a union, your union contract may give you rights, or require some procedures or processes or documentation, which are not the case for non-union employees. Your question cannot be answered without regards to your union contract. You should review the contract carefully and/or discuss the matter with your union representative.