Right now it will just ignore the additional slash and cut the string there:

henning@app01:~/repositories/kamailio/src$ killall kamailio; ./kamailio -l udp:127.0.0.1:5060//te/st -f ../etc/test.cfg -Y /tmp/ -E -L modules Listening on udp: 127.0.0.1:5060 name te Aliases: udp: localhost:5060

I think the logic could be extended easily to allow e.g. a fourth field for the listen, when we need it.