Node already exists error

I have a NEOS site with shortcut links say (A, B and C). When I try to copy a NEOS page/node from A to C it works fine. But when I copy the same node and paste it under C it shows error below. I am not sure what is going wrong here. Does anyone faced this issue before and how I can debug it and fix it? THanks in advance.

#1292503467: Node with path “/sites/umco-seminare/node-o4jdjw2g3gdax/node-ur4ebit9g0ba0/node-pq15eixbwftj4/node-2ckn0xw54ofb9” already exists.

Reference code: 201812121206129c5af3