diff --git a/taggit/managers.py b/taggit/managers.py
index 9eea6366..35d49a80 100644
--- a/taggit/managers.py
+++ b/taggit/managers.py
@@ -306,7 +306,7 @@ def set(self, tags, *, through_defaults=None, **kwargs):
                 else:
                     new_objs.append(obj)
 
-            self.remove(*old_tag_strs)
+            self.remove(*old_tags)
             self.add(*new_objs, through_defaults=through_defaults, **kwargs)
 
     @require_instance_manager
diff --git a/taggit/migrations/0001_initial.py b/taggit/migrations/0001_initial.py
index 140f0cf2..1c6c5dea 100644
--- a/taggit/migrations/0001_initial.py
+++ b/taggit/migrations/0001_initial.py
@@ -2,7 +2,7 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [("contenttypes", "0001_initial")]
+    dependencies = [("contenttypes", "0002_remove_content_type_name")]
 
     operations = [
         migrations.CreateModel(
diff --git a/taggit/models.py b/taggit/models.py
index 8d7f60bd..359d65a9 100644
--- a/taggit/models.py
+++ b/taggit/models.py
@@ -17,7 +17,7 @@ def unidecode(tag):
 
 class TagBase(models.Model):
     name = models.CharField(
-        verbose_name=pgettext_lazy("A tag name", "name"), unique=True, max_length=100
+        verbose_name=pgettext_lazy("A tag name", "name"), max_length=100
     )
     slug = models.SlugField(
         verbose_name=pgettext_lazy("A tag slug", "slug"),