Although not using pfSense for this test but I can confirm that a second client coming from same public IP is unable to connect.
On client side the log shows:
Tue Dec 20 17:20:27 2016 MANAGEMENT: >STATE:1482250827,WAIT,,,,,,
Tue Dec 20 17:22:32 2016 Restart pause, 5 second(s)
On server side no connection attempts show up in log.
Clients have their own ceritificates/commonname, no duplicate-cn.