Comment 3 for bug 1437212

Adding my thoughts from a UX perspective...

So in the case where the user is adding the same MAC address twice to one node, I agree we should just remove one and not throw an error.

IF the user is adding two separate nodes, but adding the same MAC address for each node, we should give the user an error in the modal when they click submit (it should not try to actually submit). This way the user can fix their error and submit successfully. We need to be sure the error is descriptive enough. For example "Node 1 and Node 2 are using the same MAC address. These need to be unique."