diff --git a/app/controllers/posts_controller.rb b/app/controllers/posts_controller.rb
index 64252c45220..0173cddedff 100644
--- a/app/controllers/posts_controller.rb
+++ b/app/controllers/posts_controller.rb
@@ -49,22 +49,20 @@ class PostsController < ApplicationController
     key = params_key(params)
     error_json = nil
 
-    payload = DistributedMemoizer.memoize(key, 120) do
-      post_creator = PostCreator.new(current_user, params)
-      post = post_creator.create
-      if post_creator.errors.present?
-
-        # If the post was spam, flag all the user's posts as spam
-        current_user.flag_linked_posts_as_spam if post_creator.spam?
-
-        error_json = MultiJson.dump(errors: post_creator.errors.full_messages)
+    if (is_api?)
+      payload = DistributedMemoizer.memoize(key, 120) do
+        success, json = create_post(params)
+        unless success
+          error_json = json
+          raise Discourse::InvalidPost
+        end
+        json
+      end
+    else
+      success, payload = create_post(params)
+      unless success
+        error_json = payload
         raise Discourse::InvalidPost
-
-      else
-        post_serializer = PostSerializer.new(post, scope: guardian, root: false)
-        post_serializer.topic_slug = post.topic.slug if post.topic.present?
-        post_serializer.draft_sequence = DraftSequence.current(current_user, post.topic.draft_key)
-        MultiJson.dump(post_serializer)
       end
     end
 
@@ -74,6 +72,22 @@ class PostsController < ApplicationController
     render json: error_json, status: 422
   end
 
+  def create_post(params)
+    post_creator = PostCreator.new(current_user, params)
+    post = post_creator.create
+    if post_creator.errors.present?
+      # If the post was spam, flag all the user's posts as spam
+      current_user.flag_linked_posts_as_spam if post_creator.spam?
+      [false, MultiJson.dump(errors: post_creator.errors.full_messages)]
+
+    else
+      post_serializer = PostSerializer.new(post, scope: guardian, root: false)
+      post_serializer.topic_slug = post.topic.slug if post.topic.present?
+      post_serializer.draft_sequence = DraftSequence.current(current_user, post.topic.draft_key)
+      [true, MultiJson.dump(post_serializer)]
+    end
+  end
+
   def update
     params.require(:post)
 
diff --git a/spec/components/post_creator_spec.rb b/spec/components/post_creator_spec.rb
index 76c235771a3..0c4391371bb 100644
--- a/spec/components/post_creator_spec.rb
+++ b/spec/components/post_creator_spec.rb
@@ -215,7 +215,7 @@ describe PostCreator do
 
     context "disabled" do
       before do
-        SiteSetting.stubs(:unique_posts_mins).returns(0)
+        SiteSetting.unique_posts_mins = 0
         creator.create
       end
 
@@ -229,22 +229,37 @@ describe PostCreator do
       let(:new_post_creator) { PostCreator.new(user, basic_topic_params) }
 
       before do
-        SiteSetting.stubs(:unique_posts_mins).returns(10)
-        creator.create
+        SiteSetting.unique_posts_mins = 10
+      end
+
+      it "fails for dupe post accross topic" do
+        first = create_post
+        second = create_post
+
+        dupe = "hello 123 test #{SecureRandom.hex}"
+
+        response_1 = create_post(raw: dupe, user: first.user, topic_id: first.topic_id)
+        response_2 = create_post(raw: dupe, user: first.user, topic_id: second.topic_id)
+
+        response_1.errors.count.should == 0
+        response_2.errors.count.should == 1
       end
 
       it "returns blank for another post with the same content" do
+        creator.create
         new_post_creator.create
         new_post_creator.errors.should be_present
       end
 
       it "returns a post for admins" do
+        creator.create
         user.admin = true
         new_post_creator.create
         new_post_creator.errors.should be_blank
       end
 
       it "returns a post for moderators" do
+        creator.create
         user.moderator = true
         new_post_creator.create
         new_post_creator.errors.should be_blank
diff --git a/spec/controllers/posts_controller_spec.rb b/spec/controllers/posts_controller_spec.rb
index c3aff3ab629..1a5c687cf9c 100644
--- a/spec/controllers/posts_controller_spec.rb
+++ b/spec/controllers/posts_controller_spec.rb
@@ -367,6 +367,25 @@ describe PostsController do
 
     include_examples 'action requires login', :post, :create
 
+    context 'api' do
+      it 'allows dupes through' do
+        raw = "this is a test post 123 #{SecureRandom.hash}"
+        title = "this is a title #{SecureRandom.hash}"
+
+        user = Fabricate(:user)
+        master_key = ApiKey.create_master_key.key
+
+        xhr :post, :create, {api_username: user.username, api_key: master_key, raw: raw, title: title, wpid: 1}
+        response.should be_success
+        original = response.body
+
+        xhr :post, :create, {api_username: user.username_lower, api_key: master_key, raw: raw, title: title, wpid: 2}
+        response.should be_success
+
+        response.body.should == original
+      end
+    end
+
     describe 'when logged in' do
 
       let!(:user) { log_in }
@@ -389,15 +408,14 @@ describe PostsController do
       end
 
       it 'protects against dupes' do
-        # TODO we really should be using a mock redis here
-        xhr :post, :create, {raw: 'this is a test post 123', title: 'this is a test title 123', wpid: 1}
-        response.should be_success
-        original = response.body
+        raw = "this is a test post 123 #{SecureRandom.hash}"
+        title = "this is a title #{SecureRandom.hash}"
 
-        xhr :post, :create, {raw: 'this is a test post 123', title: 'this is a test title 123', wpid: 2}
+        xhr :post, :create, {raw: raw, title: title, wpid: 1}
         response.should be_success
 
-        response.body.should == original
+        xhr :post, :create, {raw: raw, title: title, wpid: 2}
+        response.should_not be_success
       end
 
       context "errors" do