diff --git a/ldapcherry/__init__.py b/ldapcherry/__init__.py
index a948574..b28eaaa 100644
--- a/ldapcherry/__init__.py
+++ b/ldapcherry/__init__.py
@@ -486,7 +486,11 @@ def _merge_user_attrs(self, attrs_backend, attrs_out, backend_name):
         """
         for attr in attrs_backend:
             if attr in self.attributes.backend_attributes[backend_name]:
-                attrid = self.attributes.backend_attributes[backend_name][attr]
+                attr_desc = self.attributes.backend_attributes[backend_name][attr]
+                if type(attr_desc) is list:
+                    attrid = attr_desc[0]['id']
+                else:
+                    attrid = attr_desc['id']
                 if attrid not in attrs_out:
                     attrs_out[attrid] = attrs_backend[attr]
 
diff --git a/ldapcherry/attributes.py b/ldapcherry/attributes.py
index 5ddea82..dee4573 100644
--- a/ldapcherry/attributes.py
+++ b/ldapcherry/attributes.py
@@ -61,9 +61,27 @@ def __init__(self, attributes_file):
                 self.key = attrid
             for b in attr['backends']:
                 self.backends.add(b)
+                backend_attr = attr['backends'][b]
                 if b not in self.backend_attributes:
                     self.backend_attributes[b] = {}
-                self.backend_attributes[b][attr['backends'][b]] = attrid
+                if backend_attr in self.backend_attributes[b]:
+                    if type(self.backend_attributes[b][backend_attr]) \
+                        is not list:
+                            self.backend_attributes[b][backend_attr] = [
+                                self.backend_attributes[b][backend_attr],
+                            ]
+
+                    self.backend_attributes[b][backend_attr].append(
+                        {
+                            'id':attrid,
+                            'type': attr['type']
+                        }
+                    )
+                else:
+                    self.backend_attributes[b][backend_attr] = {
+                        'id':attrid,
+                        'type': attr['type']
+                    }
             if 'search_displayed' in attr and attr['search_displayed']:
                 self.displayed_attributes[attrid] = attr