Raspberry Pi configured for static IP also gets a DHCP IP - linux

Question

I've configured my Raspberry Pi for static IP. My /etc/network/interfaces looks like this:
auto lo
iface lo inet loopback
auto eth0
allow-hotplug eth0
iface eth0 inet static
address 192.168.1.2
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
Yet for some strange reason, every time I reboot my Pi or my router, my Pi gets the requested IP (192.168.1.2) but ALSO a DHCP address (192.168.1.18). So my Pi has two addresses.
Of course, this isn't necessarily a problem, I just think it's strange. Am I doing something wrong? Or not enough? My router is almost completely locked down for management, but I can enter static IPs for devices - is this necessary, if I configure the Pi to do it?
The dynamic address isn't apparent in ifconfig:
eth0 Link encap:Ethernet HWaddr b8:27:eb:5d:87:71
inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:236957 errors:0 dropped:34 overruns:0 frame:0
TX packets:260738 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:35215632 (33.5 MiB) TX bytes:70023369 (66.7 MiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:27258 errors:0 dropped:0 overruns:0 frame:0
TX packets:27258 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3397312 (3.2 MiB) TX bytes:3397312 (3.2 MiB)
yet I can ping, ssh and everything on .18 as well.

Answer 1

Since you can add multiple IP addresses to the interface eth0 as noted above, I believe the solution to your problem is to remove the auto eth0 line from your /etc/network/interfaces file.

Answer 2

The IP address attached to interface eth0 can be viewed by ip addr. May be eth0 has two IP address configured 192.168.1.2 and 192.168.1.18.
Also you can add multiple IP address to interface eth0 through
sudo ip addr add <IP address> dev eth0
If you dont want IP address 192.168.1.18 you can remove it by
sudo ip addr del 192.168.1.18 dev eth0