Implement devices with same port usage in testtool app

we need this for scale testing. number of ports is limited, so it will be better to use same port on more devices. for example: testtool will be simulating 1000 devices on 1000 ports, but generated config files will be for 100k devices:
device no.1 will use port 1
...
device no.1000 will use port 1000
device no.1001 will use port 1
..
device no.2000 will use port 1000
device no.2001 will use port 1
...