Delete Identical may be a tad dramatic, if you wanted to keep the records but make the field unique.
You could create an empty list of CODE values: codeVal = []
make an Update cursor to run through and examine the CODE in each record.
If that CODE is not in the list, add it and pass on.
If it is in the list (it is already assigned), modify it. For a numeric field, you could, for example, add a round number to it
Test it against the list again, and increment as needed until it is unique.
Calculate the CODE to this new value, and add the new value to the list.
continue to the next record......