No, it shouldn't be a problem at all with the Altiris Agent, it creates it's own id (the GUID) when it's installed.
Although you'll have duplicate SID's (Security IDs) in each PC that's not a problem the way it was thought to be:
"machine SID duplication – having multiple computers with the same machine SID – doesn’t pose any problem, security or otherwise. I took my conclusion to the Windows security and deployment teams and no one could come up with a scenario where two systems with the same machine SID, whether in a Workgroup or a Domain, would cause an issue."
http://blogs.technet.com/b/markrussinovich/archive/2009/11/03/3291024.aspx