I had a bunch of nodes already in NPM with ICMP monitoring. I ran a discovery to 'upgrade' them to SNMP monitoring. After I did that they are all showing on the Node Management page twice with the same Node ID.
I tried restarting the server, but that didn't seem to fix anything.
Also on the Node Details page, the interface is displayed twice with the same Interface ID.
No other nodes are showing twice, only the ones that were 'upgraded' to SNMP using the discovery.