diff --git a/django/forms/models.py b/django/forms/models.py
index 7f49324..76cf49c 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -377,6 +377,46 @@ class BaseModelFormSet(BaseFormSet):
                     form.save_m2m()
             self.save_m2m = save_m2m
         return self.save_existing_objects(commit) + self.save_new_objects(commit)
+    
+    def clean(self):
+        self.validate_unique()
+    
+    def validate_unique(self):
+        from django.db.models.fields import FieldDoesNotExist
+        unique_checks = []
+        for name, field in self.forms[0].fields.iteritems():
+            try:
+                f = self.forms[0].instance._meta.get_field_by_name(name)[0]
+            except FieldDoesNotExist:
+                continue
+            if f.unique:
+                unique_checks.append((name,))
+        
+        bad_fields = set()
+        for unique_check in unique_checks:
+            data = set()
+            for i in xrange(self._total_form_count):
+                form = self.forms[i]
+                if not hasattr(form, 'cleaned_data'):
+                    continue
+                if [True for field in unique_check if field in form.cleaned_data and form.cleaned_data[field] is not None]:
+                    if tuple([form.cleaned_data[field] for field in unique_check]) in data:
+                        bad_fields.add(unique_check)
+                    else:
+                        data.add(tuple([form.cleaned_data[field] for field in unique_check]))
+        
+        if bad_fields:
+            errors = []
+            for field in bad_fields:
+                if len(field) == 1:
+                    errors.append(_(u"You have entered duplicate data for %(field)s, all %(field)ss should be unique." % {
+                            'field': get_text_list(field, _("and")),
+                        }))
+                else:
+                    errors.append(_(u"You have entered duplicate data for %(fields)s, %(fields)ss should be unique together." % {
+                            'fields': get_text_list(field, _("and")),
+                        }))
+            raise ValidationError(errors)
 
     def save_existing_objects(self, commit=True):
         self.changed_objects = []
diff --git a/tests/modeltests/model_formsets/models.py b/tests/modeltests/model_formsets/models.py
index 4bf7b40..0e83be1 100644
--- a/tests/modeltests/model_formsets/models.py
+++ b/tests/modeltests/model_formsets/models.py
@@ -777,4 +777,17 @@ True
 >>> formset.get_queryset()
 [<Player: Bobby>]
 
+# Prevent duplicates from within the same formset
+>>> FormSet = modelformset_factory(Product, extra=2)
+>>> data = {
+...     'form-TOTAL_FORMS': 2,
+...     'form-INITIAL_FORMS': 0,
+...     'form-0-slug': 'red_car',
+...     'form-1-slug': 'red_car',
+... }
+>>> formset = FormSet(data)
+>>> formset.is_valid()
+False
+>>> formset._non_form_errors
+[u'You have entered duplicate data for slug, all slugs should be unique.']
 """}