diff --git a/allauth_ens/adapter.py b/allauth_ens/adapter.py
index c68a5bf..3c02f2a 100644
--- a/allauth_ens/adapter.py
+++ b/allauth_ens/adapter.py
@@ -147,7 +147,7 @@ def deprecate_clippers():
     clippers.update(provider='clipper_inactive')
 
 
-def install_longterm_adapter(fake=False, accounts=None):
+def install_longterm_adapter(fake=False, accounts=None, keep_usernames=False):
     """
     Manages the transition from an older django_cas or an allauth_ens
     installation without LongTermClipperAccountAdapter
@@ -184,7 +184,10 @@ def install_longterm_adapter(fake=False, accounts=None):
         user = accounts.get(clipper_uid, None)
         if user is None:
             continue
-        user.username = ltc_adapter.get_username(clipper_uid, data)
+
+        if not keep_usernames:
+            user.username = ltc_adapter.get_username(clipper_uid, data)
+
         if fake:
             cases.append(clipper_uid)
         else:
diff --git a/allauth_ens/management/commands/install_longterm.py b/allauth_ens/management/commands/install_longterm.py
index fdff5f1..a839555 100644
--- a/allauth_ens/management/commands/install_longterm.py
+++ b/allauth_ens/management/commands/install_longterm.py
@@ -26,6 +26,14 @@ class Command(BaseCommand):
             default=False,
             help=('Use the existing SocialAccounts rather than all the Users'),
         )
+        parser.add_argument(
+            '--keep-usernames',
+            action='store_true',
+            default=False,
+            help=('Do not apply the username template (e.g. clipper@promo) to'
+                  'the existing account, only populate the SocialAccounts with'
+                  'ldap informations'),
+        )
         parser.add_argument(
             '--clipper-field',
             default=None,
@@ -35,6 +43,7 @@ class Command(BaseCommand):
 
     def handle(self, *args, **options):
         fake = options.get("fake", False)
+        keep_usernames = options.get("keep_usernames", False)
 
         if options.get('use_socialaccounts', False):
             accounts = {account.uid: account.user for account in
@@ -55,7 +64,7 @@ class Command(BaseCommand):
         else:
             accounts = None
 
-        logs = install_longterm_adapter(fake, accounts)
+        logs = install_longterm_adapter(fake, accounts, keep_usernames)
 
         self.stdout.write("Social accounts created : %d"
                           % len(logs["created"]))
diff --git a/allauth_ens/tests.py b/allauth_ens/tests.py
index 1824b60..61bb3a4 100644
--- a/allauth_ens/tests.py
+++ b/allauth_ens/tests.py
@@ -333,7 +333,7 @@ class LongTermClipperTests(CASTestCase):
         self.assertEqual(user1.username, "test@12")
         self.assertEqual(conn.extra_data['ldap']['entrance_year'], '12')
 
-    def test_longterm_installer_from_allauth_command_username(self):
+    def test_longterm_installer_from_allauth_command_using_username(self):
         self._setup_ldap(12)
         with self.settings(
                 SOCIALACCOUNT_ADAPTER='allauth.socialaccount.'
@@ -362,6 +362,35 @@ class LongTermClipperTests(CASTestCase):
         self.assertEqual(user1.username, "test@12")
         self.assertEqual(conn.extra_data['ldap']['entrance_year'], '12')
 
+    def test_longterm_installer_from_allauth_command_keeping_username(self):
+        self._setup_ldap(12)
+        with self.settings(
+                SOCIALACCOUNT_ADAPTER='allauth.socialaccount.'
+                'adapter.DefaultSocialAccountAdapter'):
+            r = self.client_cas_login(self.client, provider_id="clipper",
+                                      username='test')
+            user0 = r.context["user"]
+            nsa0 = SocialAccount.objects.count()
+            self.assertEqual(user0.username, "test")
+            self.client.logout()
+
+        with captured_stdout() as stdout:
+            command = InstallLongterm()
+            command.handle(keep_usernames=True)
+
+        output = stdout.getvalue()
+        self.assertIn('test -> test', output)
+
+        r = self.client_cas_login(self.client, provider_id="clipper",
+                                  username='test')
+        user1 = r.context["user"]
+        nsa1 = SocialAccount.objects.count()
+        conn = user1.socialaccount_set.get(provider='clipper')
+        self.assertEqual(user1.id, user0.id)
+        self.assertEqual(nsa1, nsa0)
+        self.assertEqual(user1.username, "test")
+        self.assertEqual(conn.extra_data['ldap']['entrance_year'], '12')
+
     def test_longterm_installer_from_allauth_command_socialaccounts(self):
         self._setup_ldap(12)
         with self.settings(