We are using CA APM Enterprise Manager 10.7 SP2(Standalone configuration) .
As part of application performance monitoring, we have configured couple of .Net agents and Tomcat agents.
We have noticed, metrices are grouped under external , External%1, External%2, External%3
Release : 10.7.0
Component : APM Agents
The Enterprise Manager will assign %1 %2 etc to the agent name if it detects multiple agents with the same requested name connected at the same time. This can happen in IIS as it may start multiple worker processes for the same application. In this situation if there are active metrics for the application under each node %1 %2 etc then this is what is happening and this can be confirmed by checking on the IIS server itself to see how many workers are starting for the application in question.