After installing vRA 7.5 HF5, it is not possible to install any additional IAAS components - e.g. proxy agent / DEM. Attempt to launch the installer fails: Error: "A newer version of the product is already installed on this machine".
This is due to updated proxy agent launcher to version 22.214.171.12444 in HF5. "C:\Program Files (x86)\VMware\vCAC\Agents\<agent name>\VRMAgent.exe"
Since it is only the launcher - the "add remove programs" is not updated with this info.
To workaround this problem
Take a snapshot of IAAS machine
Take a backup of file "C:\Program Files (x86)\VMware\vCAC\Agents\<agent name>\VRMAgent.exe"
From VRA Appliance master node - download file:
Stop "VMware vCloud Automation Center Agent - <agent name>" service in IAAS
Replace the VRMAgent.exe file
Install a new vSphere Agent
Replace the VRMAgent.exe with the backup file taken in step 2
Start the service
Now attempt to install DEM/Proxy agent it should work as expected