Two primary keys in Django Python

I created a class in my models.py in Django. I first created the primary key of the user, but I now also want to add the primary id, but reports me an error: I can not have two primary keys. I do not want to spoil anything, I would highly appreciate anyone's help!

since __future__ import unicode_literals
django.db import templates
from django.contrib.auth.models import User
since django.db.models.signals import post_save
since datetime import datetime
django.db import templates

# Create your templates here.
UserProfile class (models.Model):
user = models.OneToOneField (User, on_delete = None, primary_key = True)
id = models.CharField (max_length = 100, primary_key = True)
description = models.TextField ()
criminal_record = models.TextField (default = "")
sex = models.CharField (max_length = 20, default = "")
city ​​= models.CharField (max_length = 20, default = "")
employment = models.CharField (max_length = 50, default = "")
designation = models.CharField (max_length = 200, default = "")
district = models.CharField (max_length = 100, default = "")
phone = models.IntegerField (default = 0)
head_shot = models.ImageField (upload_to = & # 39; profiles_images & # 39 ;, blank = True)
registered_at = models.DateTimeField (default = datetime.now, blank = True)
signature = models.FileField (upload_to = & # 39; signature_images & # 39 ;, blank = True)

Meta class:
command = ["user"]

    def __str __ (auto):
return from self.user.username

def create_profile (sender, ** kwargs):
if kwargs['created']:
user_profile = UserProfile.objects.get_or_create (user = kwargs['instance'])

post_save.connect (create_profile, sender = User)