RR is an older airline ticketing and Global Distribution System (GDS) code that stands for Reconfirmed. It was historically used by agents to indicate that a passenger had contacted the airline to verify their intent to fly on a specific segment. While automated ticketing has largely made manual reconfirmation obsolete, the code still appears in some legacy passenger service systems.
Heard on the job
Check the PNR to see if the return leg is showing RR or if it's still pending.