Have a trigger with name "a

{HOST.HOST1} {HOST.HOST2}{HOST.HOST3}{HOST.HOST4}" and expression "{5280-2:agent.ping.last(0)}=1&{5280-2:agent.ping.last(0)}=0&{5280:system.cpu.num.last(0)}=0&{5280-2:agent.ping.last(0)}=0"
Trigger name in Monitoring > Triggers is exploded as "a UNKNOWN{HOST.HOST2}

5280

{HOST.HOST4}

"

Note that first and second functions in expression is same;
Note that there is two different hosts.