Django how to process content of either form or the other?

Question

A user is able submit a POST request. Either by uploading a file or by using a sample on the server. Posting the file works perfect but I have trouble implementing the second part. This is my model:

class UploadFileForm(forms.Form):
    file  = forms.FileField()
    from_server = forms.BooleanField(required=False,initial=False) 

My template. I thought it best to use two forms. But I fail to check on the content/type/key of the incoming data in my view.

<div class="fieldWrapper">
    <form action="flot" enctype="multipart/form-data" method="post">{% csrf_token %}
        <label for="id_file">File:</label>
        {{ form.file }}
        <input id="upload" type="submit" value="Upload">
</form>
</div>

<div class="fieldWrapper">
<form action="flot" method="post">{% csrf_token %}
    <label for="id_from_server">Gebuik een sample file op de server</label>
             {{ form.from_server }}
        <input id="server" type="submit" value="Go" name="Go">
        <!--<input id="upload" type="submit" value="Go">-->
</form>
</div>

Here is my view. I don't know exactly how to check the incoming data on from which form they where submitted. See request.POST.getlist('Go') for my final attempt. Test-wise I will return a Http404.

if request.method == 'POST':
    form = UploadFileForm(request.POST, request.FILES)
    if form.is_valid(): 
        if 'Go' in request.POST.getlist('Go'): 
            raise Http404 
        else:
            err, line_z1, line_z2 = handle_uploaded_file(request.FILES['file'])
            if err == None:
                return render_to_response('flot.html',
                                          {
                                          'form': form,
                                          'line1':simplejson.dumps(line_z1),
                                          'line2':simplejson.dumps(line_z2)
                                          },
                                          context_instance=RequestContext(request))
    else:
        form = UploadFileForm()
        return render_to_response('flot.html',
        {'form': form,
         'error': err
         },
         context_instance=RequestContext(request))

else:
    form = UploadFileForm()
    return render_to_response('flot.html',
                             {'form': form},
                             context_instance=RequestContext(request))