title: Images getting duplicated on django_forms
body: <p><br />
  I have a web template where i am uploading two photos on different fields, but when i save the form one of them gets replaced with the other.<br />
  Ex. i upload an image on field-1 but when i save the form the image gets saved on field-1 and field-2, it happens the both ways, when uploading something on field-2 also gets replaced on field-1</p>
  <p>FormCode</p>
  <pre><code>class CustomLPForm(forms.ModelForm):
      address = forms.CharField()
      we_ara_picture = forms.ImageField( required=True)
      landing_image = forms.ImageField( required=True)
      landing_image_mobile = forms.ImageField( required=False)
  
      def __init__(self, *a, **kw):
          super(CustomLPForm, self).__init__(*a, **kw)
  
      class Meta:
          model = CustomLP
      
          exclude = (&quot;date_created&quot;, &quot;date_modified&quot;, &quot;date_removed&quot;, &quot;agency&quot;)
          error_messages = {
              'about': {
              'max_length': _(&quot;La descripcion es muy larga.&quot;),
              },
          }
  </code></pre>
  <p>Model</p>
  <pre><code>    class CustomLP(Model):
  
      agency = models.OneToOneField(
          Agency, related_name=&quot;landing_customization&quot;, verbose_name=_(&quot;Agency&quot;), unique=False)
      we_are = models.TextField(verbose_name=_(&quot;We are&quot;), null=True, blank=True)
      we_ara_picture = models.ImageField(
          upload_to=logo_picture_upload_to,
          verbose_name=_(&quot;we ara picture&quot;), null=True, blank=True)
      landing_image = models.ImageField(
          upload_to=logo_picture_upload_to,
          verbose_name=_(&quot;landing_image&quot;), null=True, blank=True)
      landing_image_mobile = models.ImageField(
          upload_to=logo_picture_upload_to,
          verbose_name=_(&quot;landing_image_mobile&quot;), null=True, blank=True)
  </code></pre>
  <p>View</p>
  <pre><code>    def customize_landing(request):
          agency = request.user.profile.user_agency
          if request.POST:
              landing = agency.landing_customization
          
  
              landing_form = CustomLPForm(
              request.POST, request.FILES, instance=landing, prefix=&quot;customlp&quot;)
              if not landing_form.is_valid():
                  msg = u&quot;Ocurrió un error al intentar configurar la web.&quot;
                  messages.error(request, msg)
              else:     
              
                  landing = landing_form.save(commit=False)
                  landing.agency = agency
              
                  storaged_agency = landing.agency
  
                  storaged_agency.latitude = request.POST['latitude']
                  storaged_agency.longitude = request.POST['longitude']
                  storaged_agency.microsite_domain = request.POST['customlp-microsite']
                  storaged_agency.address = request.POST['customlp-address']
  
                  storaged_agency.save()
                  landing.cards = json.dumps(cards_dict)
                  landing.save()
                  msg = u&quot;El sitio web de la agencia ha sido publicado.&quot;
                  messages.success(request, msg)
  </code></pre>