fix VPNUser creation

lambdainst/models.py

@@ -4,6 +4,7 @@ from django.db import models
 from django.contrib.auth.models import User
 from django.utils.translation import ugettext as _
 from django.db.models.signals import post_save
+from django.db import IntegrityError
 from django.dispatch import receiver
 from constance import config as site_config
 from django_lcore.core import LcoreUserProfileMethods, setup_sync_hooks, VPN_AUTH_STORAGE
@@ -99,8 +100,11 @@ setup_sync_hooks(User, VPNUser)
 
 @receiver(post_save, sender=User)
 def create_vpnuser(sender, instance, created, **kwargs):
-    if created and not instance.vpnuser:
+    if created:
+        try:
             VPNUser.objects.create(user=instance)
+        except IntegrityError:
+            pass
 
 
 class GiftCode(models.Model):