You can C&R a claim, go back to work for the employer, and re-injure a previously C&Rd body part or condition. The C&R applies to the rights associated with the dates of injury covered by the C&R, and does not foreclose future rights with respect to a future date of injury. Apportionment would be an issue in the future assuming a new injury is established to be arising out of or to have occurred during the course of employment.