Samsung might be working on a new variant of Galaxy S5 which runs on the company's Tizen platform. According to the Indian import tracking site Zauba, three units of ‘Samsung Galaxy S5 Tizen Test Phone' have been received by Chennai Air Cargo (India) for testing purposes. The price of each unit is listed at INR 54,404 ($905), which is actually costlier than the Galaxy S5's retail price. This also explains why Samsung Apps Store was recently renamed to Samsung Galaxy Apps Store.
However, it remains to be seen if such a phone will launch in markets anytime soon, or whether it's simply being used as a test platform for future devices. More info will hopefully crop up in the future to answer that question.