checking username duplicates seems to work

auth.py

@@ -24,6 +24,8 @@ def register():
             error = 'Username is required.'
         elif not password:
             error = 'Password is required.'
+        elif dbsession.query(User).filter(User.username == username).first() != None:
+            error = "Username already exists, please choose another one"
 
         if error is None:
             try: