Does FreeBSD issue messages about MAC/IP conflicts?

[Yuri]

I accidentally had two machines having the same wifi MAC address.
Wifi router gave them both the same local IP address and they both  
could somewhat connect to the outside world, but connections were flaky.

No messages about IP/MAC conflicts appeared in dmesg log.

Vague memories from the long ago past remind me that Windows was  
issuing IP conflict messages in the local wired network.

Why doesn't FreeBSD complain at leat about the IP conflict?

FreeBSD-8.0-STABLE, ath0 interface.

Yuri