Strange question - second subnet in my router

Dear all,

I have a pc with linux which play as router in my office.
Here is my originally setting :

192.168.1.x/24 --LAN-- (192.168.1.1 (PC-linux) 192.168.17.212) --WAN--

2 NIC in my PC-linux, one of them is eth0(192.168.1.1) as my lan gateway
and the other eth1(192.168.17.212) as my wan ip.All PCs in lan access
internet via PC-linux.
For some reason, I have to extend my PC-linux ability to handle the
second lan. And I use "ip addr" command to achieve this request. My
command is - ip addr add 192.168.111.111/24 dev eth0. I can attach 2nd
lan to eth0 successfully and it can access internet smoothly.
The question is that when PCs in 2nd lan try to access my PC-linux's WAN
IP(192.179.17.212), PC-linux always send these packets to WAN instead of
sending to 2nd lan.But my 1st lan(192.168.1.x) can access without any
problem. At first I think this may be a iptable or routed issue, but
after flush iptable and check routing table I still can't resolve this
problem.

My routing table is

# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
192.168.17.0 * 255.255.255.0 U 0 0 0 eth1
192.168.111.0 * 255.255.255.0 U 0 0 0 eth0
default 192.168.17.70 0.0.0.0 UG 0 0 0 eth1

My ip address list is

# ip addr l
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
6: eth1: <BROADCAST,NOTRAILERS,UP> mtu 1500 qdisc htb qlen 100
link/ether 00:04:ed:45:88:25 brd ff:ff:ff:ff:ff:ff
inet 192.168.17.212/24 brd 192.168.17.255 scope global eth1
inet 192.168.17.212/32 scope global eth1
7: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc htb qlen 100
link/ether 00:26:66:45:88:24 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.1/24 brd 192.168.1.255 scope global eth0
inet 192.168.111.111/24 scope global eth0


Any ideas??

Thanks..