There is a sequence number used when sending discovery messages. This sequence number is intended to detect stale messages. However it could be misleading if the peer reboots. In this case the peer's sequence number will reset. The node will think that all information being sent to it is stale, while in reality the peer might've changed configuration.
There is no reliable why to know whether a peer rebooted, so we'll always assume that the messages we're receiving are valid. So we'll operate on the first come first serve basis.