The protocol address belong to uplink interface of the DLR (most of the time we call it Transit interface).
Lets say you give it ip address 192.168.10.3
Now when you try to setup the management ip address to be on the same subnet 192.168.10.4 you need to select interface.
From what i see you can't chose this Transit interface. that mean you would need to chose different ip address.
1. why you need managment address for DLR ?
2. why it need to be same ip address as protocol address ?