Every time I encrypt the data, I generate a different IV. Suppose the attacker has access to all files ever encrypted. They don't know the key, but they do know the IV. The problems is: if I save the same data with the same key several times, I generate different encrypted data. Theoretically, this could give the attacker some information about the key or the data, assuming they know that neither have changed. Should I worry about this?
This is mostly a theoretical question. In practice I could simply check if the data or the key have changed. If not, then I don't change the encrypted data.