test setup :

• template "a" with an item with key "test"
• template "b" with no items (or different items from template "a")
• template "c" with an item with key "test"
• host "host", linked to template "c"
• discovery rule that discovers host "host"
• discovery action that links discovered host to templates "a" and "b"

result :
linking fails, as zabbix finds the conflicting "test" item between templates "a" and "c"

expected :
zabbix would still complain about the conflicting item, but would link template "b", as it does not conflict