"RLException: roslaunch file contains multiple nodes named [/hokuyo]." is thrown if primary and secondary lasers are both enabled. This is because both envars launch an instance of the urg_node with the same name "hokuyo". Adding a "_secondary" suffix to the secondary laser node resolves this issue.
"RLException: roslaunch file contains multiple nodes named [/hokuyo]." is thrown if primary and secondary lasers are both enabled. This is because both envars launch an instance of the urg_node with the same name "hokuyo". Adding a "_secondary" suffix to the secondary laser node resolves this issue.