Presently, the API allows import or generation of AES keys using the "AES-CTR" or "AES-CBC" algorithms. However the AES mode is not really a property of the key.
Consider removing the generateKey operation from AES-CTR and AES-CBC and defining a new algorithm, "AES", supporting generateKey, importKey and exportKey.
This is a design choice, not a defect.
The re-use of an AES key in multiple modes of operation can be fatal to the underlying security guarantees. A key used to protect or unprotect data with a particular algorithm should not be reused for any other algorithms. See also the discussion of Key Tainting.