Recently came accross with this issue where the push installation of RAWS fails with error 1602 on multiple servers. On doing a manual installation that too fails stating that another instance of installation is already running. I checked in the task manager and found no instance of "msiexec" running. Found that there is "setup.exe" listed in the process running in task manager. After killing this process, the manual installation went smoothly. I checked other servers and found "setup.exe" running in the task manager. After ending this process on all the servers I was able to install the remote agent through push mode successfully.