Django: Overriding the clean() method in forms - question about raising errors

I've been doing things like this in the clean method:

if self.cleaned_data['type'].organized_by != self.cleaned_data['organized_by']:
      raise forms.ValidationError('The type and organization do not match.')
if self.cleaned_data['start'] > self.cleaned_data['end']:
      raise forms.ValidationError('The start date cannot be later than the end date.')

But then that means that the form can only raise one of these errors at a time. Is there a way for the form to raise both of these errors?

EDIT #1: Any solutions for the above are great, but would love something that would also work in a scenario like:

if self.cleaned_data['type'].organized_by != self.cleaned_data['organized_by']:
      raise forms.ValidationError('The type and organization do not match.')
if self.cleaned_data['start'] > self.cleaned_data['end']:
      raise forms.ValidationError('The start date cannot be later than the end date.')
super(FooAddForm, self).clean()

Where FooAddForm is a ModelForm and has unique constraints that might also cause errors. If anyone knows of something like that, that would be great...