Multi source, can not create multiple domains on the same master

Having a spider proxy to shard data on multiple schema into blackhole tables i now need some slave to read from the same master but using separate schema replicate-do-db. Every slave is replicating a couple of pre shard schema in asynchrone but in all case every slave can serve all the shards .

change master 'dshard19' to master_host='192.168.0.30' , master_port=5013, master_user='skysql', master_password='skyvodka', master_log_file='mysql_sandbox5013-bin.000002', master_log_pos=6176;
ERROR 1934 (HY000): Connection 'dshard19' conflicts with existing connection 'dshard01'

What i don't get is during a prove of concept at a client we did not get this issue and have been able to build the same solution on the same release number only difference all instances was on dedicated servers .

Can we introduce a parameter to enable multi source replication to a single master