diff --git a/activerecord/lib/active_record/association_preload.rb b/activerecord/lib/active_record/association_preload.rb
index a89f5f5459edb6425dc41f0029e7594511852059..cc657dc4338c9b49a387157dc57a0d34ef729c19 100644
--- a/activerecord/lib/active_record/association_preload.rb
+++ b/activerecord/lib/active_record/association_preload.rb
@@ -10,7 +10,7 @@ module ClassMethods
       # preload_options is passed only one level deep: don't pass to the child associations when associations is a Hash
       protected
       def preload_associations(records, associations, preload_options={})
-        records = [records].flatten.compact
+        records = [records].flatten.compact.uniq
         return if records.empty?
         case associations
         when Array then associations.each {|association| preload_associations(records, association, preload_options)}
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index cfdd33d6e8b43052f5d881642a7a5b9906f1cf57..5162f859aa4929226da95364de50e80e5d2465c5 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1536,8 +1536,10 @@ def remove_duplicate_results!(base, records, associations)
                   is_collection = [:has_many, :has_and_belongs_to_many].include?(reflection.macro)
 
                   parent_records = records.map do |record|
-                    next unless record.send(reflection.name)
-                    is_collection ? record.send(reflection.name).target.uniq! : record.send(reflection.name)
+                    descendant = record.send(reflection.name)
+                    next unless descendant
+                    descendant.target.uniq! if is_collection
+                    descendant
                   end.flatten.compact
 
                   remove_duplicate_results!(reflection.class_name.constantize, parent_records, associations[name]) unless parent_records.empty?
diff --git a/activerecord/test/cases/associations/eager_test.rb b/activerecord/test/cases/associations/eager_test.rb
index 1ea101f3c970c65b72d9d022b72e01ff796a1816..0ac5054b456fe81d4db35af82d7a1b12c220b6c2 100644
--- a/activerecord/test/cases/associations/eager_test.rb
+++ b/activerecord/test/cases/associations/eager_test.rb
@@ -67,6 +67,32 @@ def test_duplicate_middle_objects
     end
   end
 
+  def test_including_duplicate_objects_from_belongs_to
+    popular_post = Post.create!(:body => "I like cars!")
+    comment = popular_post.comments.create!(:body => "lol")
+    popular_post.readers.create!(:person => people(:michael))
+    popular_post.readers.create!(:person => people(:david))
+
+    readers = Reader.find(:all, :conditions => ["post_id = ?", popular_post.id],
+                                :include => {:post => :comments})
+    readers.each do |reader|
+      assert_equal [comment], reader.post.comments
+    end
+  end
+
+  def test_including_duplicate_objects_from_has_many
+    car_post = Post.create!(:body => "I like cars!")
+    car_post.categories << categories(:general)
+    car_post.categories << categories(:technology)
+
+    comment = car_post.comments.create!(:body => "hmm")
+    categories = Category.find(:all, :conditions => ["posts.id=?", car_post.id],
+                                 :include => {:posts => :comments})
+    categories.each do |category|
+      assert_equal [comment], category.posts[0].comments
+    end
+  end
+
   def test_loading_from_an_association
     posts = authors(:david).posts.find(:all, :include => :comments, :order => "posts.id")
     assert_equal 2, posts.first.comments.size
diff --git a/activerecord/test/fixtures/people.yml b/activerecord/test/fixtures/people.yml
index 22c64afb7095885132764345409be4868e5984dc..d5a69e561dc6139e113f695bce35f1324083eebe 100644
--- a/activerecord/test/fixtures/people.yml
+++ b/activerecord/test/fixtures/people.yml
@@ -1,3 +1,6 @@
 michael:
   id: 1
-  first_name: Michael
\ No newline at end of file
+  first_name: Michael
+david:
+  id: 2
+  first_name: David
\ No newline at end of file