Prevent control numbers from duplicating

Prevent control numbers from duplicating

In maintain_control_numbers(), if you have more than one 001 or
003, and at least one is the correct one, you will end up
duplicating the correct number every time the record is saved.

For example, if the incoming record was record ID # 12345, and
the record contained:

001: 12345
001: ocm10202

... then after maintain_control_numbers() ran, the record would
contain:

001: 12345
001: 12345

Also, clean up some leftovers from the refactor I suggested in the
previous commit.

Signed-off-by: Dan Wells <dbw2@calvin.edu>
Signed-off-by: Dan Scott <dscott@laurentian.ca>