Same OND can be added multiple times

Description

One can add the same OND, i.e., identified by the IP and port as transport address to the controller. Each time a new OND is created. However, the controller does stop asking the actual OND after having multiple entries for the same transport address.

Expected Behavior

Add same OND only once and refuse adding it again.

Actual Behavior

Allows adding same OND over and over.

Possible Fix

Double-check if OND is already in controller before adding it.

Steps to Reproduce

Context

Your Environment

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