You cannot "remap" a key which is assigned a special function; what you need to do is unmap the key. A key which is mapped as the default to perform a specific action is during a specific phase of TCC operation is unmapped by one of the directives NormalKey, NormalEditKey, NormalListKey, or NormalPopupKey. See HELP for the list of key mappings and the applicability of each of these unmapping directives.
Oh, and you can always assign more than one key to a specific operation. Assigning the same key to more than one operation in the same input phase is an error; typically the first assigned operation results, but there are no guarantees.