We are replacing several Windows computers. If I use the Remote installation and use get hosts automatically, then select all the computers in the domain, will this reinstall the agent, or will the installation recognize that the agent is already installed and skip that machine?
It will not reinstall the agent, but will install the latest version in its place. So if the agent was already installed with the latest it will copy those same files over and reconnect. If it was an older version of the agent then it will copy over the newer files and reconnect as the newer version.
It is ok to do this, but if you are more specific about which ones to send it to then it will save you time.