Unable to benefit from Zabbix auto-registration process with hosts having multiple hostnames. Hosts using multiple comma-separated Hostname values (ie. Hostname=OS-LINUX,DB-MYSQL) have to share single HostMetadata parameter. Therefore it is impossible to use separate conditions and evaluate separate operations for host auto-registration. 

Steps to reproduce:

Say we have a single Linux based host named ZBX-PROXY that acts as Zabbix proxy with MySQL database and we want it to be monitored as two separate hosts:

Host 1: OS-LINUX (OS level monitoring)
Host 2: DB-MYSQL (DB level monitoring)

1. /etc/zabbix/zabbix_agent2.conf of ZBX-PROXY:

ServerActive=ZBX-PROXY
Server=ZBX-PROXY
Hostname=OS-LINUX,DB-MYSQL
HostMetadataItem=system.uname

1. Auto-registration actions configured (see the screenshot):
   

Result:

Both OS-LINUX and DB-MYSQL get auto-registered, added to the host group "OS - Linux" and linked to template "Template OS Linux" (see the screenshot):

Expected:
1) a way to pass HostMetadata and HostMetadataItem info on a hostname basis not as a single shared parameter or 2) to find a workaround for raised problem. Using hostname as an auto-registration action condition is out of the question because in most cases we use GUID-s instead of simple hostnames. 

Expectation is that both hosts get added to separate host groups and get linked with different templates.  

Suggested config: 

ServerActive=ZBX-PROXY
Server=ZBX-PROXY
Hostname=OS-LINUX,DB-MYSQL
HostMetadataItem.OS-LINUX=system.uname    # Metadata passed only to OS-LINUX
HostMetadata.DB-MYSQL=mysql               # Metadata passed only to DB-MYSQL
#HostMetadataItem=system.uname            # Metadata passed to all hosts. Takes precedence over HostMetadata.* and HostMetadataItem.* parameters