When configuring 2 VLANs to be on the same subnet, only one works.

[Eitan Shefi]

I'm testing a NIC driver.
I use 2 directly connected FreeBSD-7.0 hosts.
When I create 2 VLANs for the same interface (mtnic0), on each host, and
configure the VLANs on each host to be on the same subnet:
ping works only to one of the VLANs.
 
I run:
On sw259: 
/sbin/ifconfig vlan1 create vlan 1 vlandev mtnic0
/sbin/ifconfig vlan2 create vlan 2 vlandev mtnic0
/sbin/ifconfig vlan1 91.154.12.5 netmask 255.0.0.0
/sbin/ifconfig vlan2 91.155.12.5 netmask 255.0.0.0
 
On sw260: 
/sbin/ifconfig vlan1 create vlan 1 vlandev mtnic0
/sbin/ifconfig vlan2 create vlan 2 vlandev mtnic0
/sbin/ifconfig vlan1 91.154.12.6 netmask 255.0.0.0
/sbin/ifconfig vlan2 91.155.12.6 netmask 255.0.0.0
 
Now on sw259 run: 
ping 91.154.12.6 - works. 
ping 91.155.12.6 - does not work. 
 
I saw the same behavior also when running via a different NIC.
 
 
Is this expected ?
 
 
Thanks,
Eitan.