removed test for server incorrectly sending duplicate message.

checks for the same are dependent on connection serial.

spec/acceptance/realtime/message_spec.rb

@@ -418,41 +418,6 @@ def publish_and_check_extras(extras)
       end
     end
 
-    context 'server incorrectly resends a message that was already received by the client library' do
-      let(:messages_received) { [] }
-      let(:connection)        { client.connection }
-      let(:client_options)    { default_options.merge(log_level: :fatal) }
-
-      it 'discards the message and logs it as an error to the channel' do
-        first_message_protocol_message = nil
-        connection.__incoming_protocol_msgbus__.subscribe(:protocol_message) do |protocol_message|
-          first_message_protocol_message ||= protocol_message unless protocol_message.messages.empty?
-        end
-
-        channel.attach do
-          channel.subscribe do |message|
-            messages_received << message
-            if messages_received.count == 2
-              # simulate a duplicate protocol message being received
-              EventMachine.next_tick do
-                connection.__incoming_protocol_msgbus__.publish :protocol_message, first_message_protocol_message
-              end
-            end
-          end
-          2.times { |i| EventMachine.add_timer(i.to_f / 5) { channel.publish('event', 'data') } }
-
-          expect(client.logger).to receive(:error) do |*args, &block|
-            expect(args.concat([block ? block.call : nil]).join(',')).to match(/duplicate/)
-
-            EventMachine.add_timer(0.5) do
-              expect(messages_received.count).to eql(2)
-              stop_reactor
-            end
-          end
-        end
-      end
-    end
-
     context 'encoding and decoding encrypted messages' do
       shared_examples 'an Ably encrypter and decrypter' do |item, data|
         let(:algorithm)      { data['algorithm'].upcase }