there can only be one

lib/ansible/inventory/data.py

@@ -238,6 +238,7 @@ class InventoryData(object):
             # match on host name/inventory_hostname is unique id
             if hostobj.name == host.name:
                 del self.hosts[hostobj]
+                break
 
         for group in self.groups:
             g = self.groups[group]

lib/ansible/inventory/group.py

@@ -243,6 +243,7 @@ class Group:
             for hostobj in self.hosts:
                 if hostobj.name == host.name:
                     self.hosts.remove(hostobj)
+                    break
             self._hosts.remove(host.name)
             host.remove_group(self)
             self.clear_hosts_cache()