The ARM DS-5 debugger supports connecting to only a single USB Blaster debug target at a time on a given host. If you attempt to launch multiple USB Blaster debug connections, DS-5 displays error messages such as the following:
Unable to connect to Altera-SoCFPGA-HardwareLib-FPGA-CV-GNU-Debug.
The script file (debug_server.py) failed during execution:
Port 3010 is already in use
Use a separate PC or virtual machine to debug each target.