MySQL multi level replication breaks constantly

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http://serverfault.com – I have replication setup as follows Master A ----> Slave B ------> Slave C \-------> Slave D \------> Slave E - H I use this setup because I need a local copy at the office server (that is slave C). I don't want to put extra strain on Master A because it's already receiving all of the inserts and extra load from the slaves connections. So I setup multi level replication. Master A replicates to Slave B, which in turn is master to Slave C. Replication from A -> B works perfectly. Replication from B -> C breaks constantly with "Duplicate key" errors. I have the relay (HowTos)