diff --git a/activerecord/lib/active_record/associations/association_collection.rb b/activerecord/lib/active_record/associations/association_collection.rb
index a7e1516..dbadb08 100644
--- a/activerecord/lib/active_record/associations/association_collection.rb
+++ b/activerecord/lib/active_record/associations/association_collection.rb
@@ -349,7 +349,7 @@ module ActiveRecord
             begin
               if !loaded?
                 if @target.is_a?(Array) && @target.any?
-                  @target = find_target + @target.find_all {|t| t.new_record? }
+                  @target = (find_target - @target) + @target
                 else
                   @target = find_target
                 end
diff --git a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
index 5e8b2ca..b97bb73 100644
--- a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
@@ -299,7 +299,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     dev.projects << projects(:active_record)
     dev.projects << projects(:active_record)
 
-    assert_equal 3, dev.projects.size
+    assert_equal 2, dev.projects.size
     assert_equal 1, dev.projects.uniq.size
   end