I would like to know what will happen if there is 2 networks on 2 diff sites.
Will all the routing affected? or only the particular network?
Without topology details this answer is at a very high level.
If you have the same network/subnet in 2 different locations then
1) Both networks will be unable to communicate with each other for obvious reasoons ie. host 192.168.5.10 wants to communcate with host 192.168.5.20 in the remote subnet but if course it will not get off it's loca subnet.
2) Other locations/subnets will be affected in that they will be directed by the routing protocol to the location with the best metric so there is no guarantee that when you want to talk to 192.168.5.10 you are being directed to the right one.