When you have multiple devices connected to a switch and two devices have the same IP address, sometimes an error message will appear on a device if a duplicate IP address is found. Is this message part of the Windows operating system or a message generated by the switch?
When you have a serial connection between two routers and they have the same IP address and subnet mask (such as 18.104.22.168 / 255.255.255.252), it appear neither router has any errors and you can ping that IP address from either router with no problem. Of course, if you try to ping what should be the OTHER IP address (22.214.171.124 / 255.255.255.252), you will get "no reply" and possibly spend several minutes 'troubleshooting the issue' until you realize there is no 126.96.36.199, but instead two 188.8.131.52's. I guess I am asking the serial ports / routers can't detect there is a duplicate IP address and give an error for this configuration mistake?
Duplicate IP addresses
When your computer detects it, it's the computer that's doing it. According to IPv4 Address Conflict Detection- RFC 5227 , both devices are involved. Both devices are detecting what each has sent. For example, The Switch is detecting that the PC has an IP address mapped to a MAC address and the switch may have that same IP address in the MAC address table linked to a different MAC address. So each is detecting and reporting what the other side has said.
On the serial link, you do not get a message of duplicate address but the unusual thing is that if two router interfaces are connected to the same switch, both routers will generate an error message. But I'm seeing the same thing you're seeing on the serial interface, no error messages. But it's not normally a problem, I do this often and I often suspect it as being a wrong address i have typed. No, it's not as helpful but I believe it has to do with the point-to-point nature of serial connections.