BOLT#7 outlines in the rules for receiving channel_announcement messages, that any previously known channel with differing node_ids, should result in the blacklisting of all associated nodes for both the current message and the previously known channel.
if it has previously received a valid channel_announcement, for the same transaction, in the same block, but for a different node_id_1 or node_id_2:
- SHOULD blacklist the previous message's node_id_1 and node_id_2, as well as this node_id_1 and node_id_2 AND forget any channels connected to them.