1) 2 devices respond to ping. 2) Echo requests are getting duplicated in network and end host is responding to each. 3) End device receives correct echo request, and the response is getting duplicated somewhere in the network. To track this down, use Wireshark to sniff the packets first at the client generating the pings.
To open any UDP ports, you can do the following: Go to Control Panel> System and Security and Windows Firewall. Advanced settings > right-click Inbound Rules and select New Rule. Add the port(s) you want to open and click Next. Select UDP protocol and the port(s) number(s) into the next window and click Next. Select Allow the connection and hit How to Allow Pings (ICMP Echo Requests) Through Your Mar 28, 2019 How to enable and disable PING ICMP in Windows 10 Firewall
How to enable and disable PING ICMP in Windows 10 Firewall
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How to Allow Pings (ICMP Echo Requests) Through Your Mar 28, 2019 How to enable and disable PING ICMP in Windows 10 Firewall