What does this error mean "A slave with the same server_uuid/server_id as this slave has connected to the master;"?

Upon searching for this, the main cause of this error is usually when using snapshots or cloning the machine. But I did not do this. I perform mysqldump --master-data=2 on the master then restore the dump on my slave server. Then start the slave on the position indicated on the outfile. Any idea on what caused this? I am running a multi-source replica and this error is from just 1 source. here is the complete error: >Got fatal error 1236 FROM MASTER WHEN reading DATA FROM BINARY LOG: 'A slave with the same server_uuid/server_id as this slave has connected to the master; the first event 'VM1-bin.000006' at 641809774, the last event read from '/binlogdata/VM1-bin.000009' at 146836375, the last byte read from '/binlogdata/VM1-bin.000009' at 146836375.';