do I understand correctly that you want to remove several unknown interfaces from several nodes? If that is the case, you can go to Manage Nodes page and either search for the interfaces or expand parent nodes. Then you will be able to check all the interfaces that you want to remove and then just hit the Delete button.
Is it picking the Network cards back up after a rediscovery? I'm not too sure of how NPM detects interfaces.. but if it is looking at the Device Manager, then ghosted nics in the device manager could be the root problem.
Go to device manager, Click View, Click Show hidden devices, and see if you have any grayed out network cards. It happens often as people play around with configurations of systems and add/delete network cards. Microsoft incrementally adds these devices to thre registry and never removes them. A tell tale sign is when you look at network connections in the VM's operatins system and you see Local Area Connection 2, rather than just Local Area Connection.
I have this problem as well, from what I can tell it's on servers I've done a P2V on and it's still got the old NIC from the physical server. I've tried what Lukas suggested but it doesn't do anything, it looks like the index information might be messed up for the interface as it shows a "-1" in the interface details for these.
Also checked for any hidden devices as uidzer0 suggested, but nothing, any help would be appreciated.