Why after reboot, an extra default route gets added in the system ?

Issue

• At every system reboot, extra default route like below gets added in the system.

~]# cat route 
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
[...]
0.0.0.0         192.168.A.B     0.0.0.0         UG    0      0        0 eth3  <<--- [1]
0.0.0.0         10.5.X.Y        0.0.0.0         UG    0      0        0 eth3  <<--- [2]
~]#

• Even after deleting route like route del -net 0.0.0.0 netmask 0.0.0.0 gw 10.5.X.Y same gets added after system reboot. Why ?