Improve TenantPrivilege
diff --git a/xos/core/models/service.py b/xos/core/models/service.py
index 83fd3e8..82d6263 100644
--- a/xos/core/models/service.py
+++ b/xos/core/models/service.py
@@ -829,9 +829,6 @@
     tenant = models.ForeignKey('Tenant', related_name="tenantprivileges")
     role = models.ForeignKey('TenantRole', related_name="tenantprivileges")
 
-    class Meta:
-        unique_together = ('user', 'tenant', 'role')
-
     def __unicode__(self):  return u'%s %s %s' % (self.tenant, self.user, self.role)
 
     def save(self, *args, **kwds):