MASTER CONNECTION

When two slaves with same UUID are configured to replicate from a
single master, the I/O thread of the slaves keep reconnecting and
generating a new relay log files almost without new content.

Analysis:

The master server do not allow two slave connections with same UUID.

Once a new connection is made from a slave with a given UUID, the
master disconnects the older connection, keeping only one slave
connection per slave UUID.

On the other side, as the master doesn't report any errors to
the slave, the I/O thread of the disconnected slave will try to
reconnect, generating a new relay log file.

Fix:

The master now throws an error to the slave once detecting a
duplicate UUID. By receiving an error from the master, the I/O
thread will not try to reconnect anymore.