Just recently noticed this happening, I know it didn't used to act this way so I am assuming either someone at our office changed a setting or it is a reult of an update.
We set up and configure the workstations for our clients at our office, then deliver them to the clients office. When we install the agent while the machine is as our office, the agent appears as the ComputerName. Once we take the computer on site to our clients office (different network, different GW), the the agent is duplicated in K with the name ComputerName-1.
I am assuming that the system is seeing the agent from 2 different networks or gateways (first from ours, then from the clients), and it creates 2 agents in K thinking they are 2 different machines.
Anyone know how to turn this off?
I had a similar problem after we would rebuild a computer. It would get the "-1" after the name, and I found that even if the old agent is no longer checking in, if the agents GUID's don't match then it thinks a new computer. So I don't think it''s subnet/gateway related as we have many different subnets and gateways ourselves, but more likely a GUID issue. I would first check that no one at the second site is reinstalling the agent (perhaps not knowing it's already on there?), as this would cause the issue your having.
I know it's not an answer, but some more information might help.
I saw this behavior about a year ago. It was due to a bug in SQL server SP2. Make sure your SQL is fully patched.