"The IP address 10.0.20.31 you have entered for this network adapter is already assigned to another adapter 'Microsoft Virtual Machine Bus Network Adapter #2' 'Microsoft Virtual Machine Bus Network Adapter #2' is hidden from the Network Connections folder because it is not physically in the computer. If the same address is assigned to both adapters and they both become active, only one of them will use this address. This may result in incorrect system configuration. Do you want to enter a different IP address for this adapater in the list of IP addreses in the Advanced dialog box?"
By changing the virtual network on the Hyper-V host, I have managed to create a ghost network adapter in my hyper-v VM!
To see the hidden adapter >
1. launch command prompt - start > run > cmd [enter]
2. type set devmgr_show_nonpresent_devices=1 [enter]
3. type start devmgmt.msc [enter]
4. from menu bar select 'View' drop down and select 'Show hidden devices'
To remove the (now visible) adapter >
1. locate the adapter in device manager under 'network adapters'
2. right-click it and select 'uninstall device'