Colo. Rev. Stat. § 42-3-206
Persons who have been approved to be issued a license plate before July 1, 2003, pursuant to this section as it existed on July 1, 2003, shall be issued such plate, shall be authorized to continue using such plate, and shall not be required to pay additional fees beyond the existing taxes and fees imposed for motor vehicle registration. Such issuance of license plates that contain only two alphabetic figures and up to four numeric figures shall be issued as personalized license plates pursuant to section 42-3-211, which are a flat-style license plate. If the same alphanumeric combination is issued to multiple vehicles, the department shall compare the last four numbers of the vehicle identification number of the motor vehicles to which such plates are issued and issue such alphanumeric combination only to the vehicle with the lowest last four numbers.
C.R.S. § 42-3-206
This section is similar to former § 42-3-113.5 as it existed prior to 2005.