Even the best of hotel distribution systems of today can't do away with the menace of dealing with duplicate hotels. In fact, some systems take pride in counting their 'large' inventory.
At roomsXML, it's a different story though. Out here, we value quality over quantity. When we say we have 87,350* hotels, we mean 87,350 hotels. No less, no more.
We spent over 6,500 man-hours in building a system void of duplicate hotels. Well, we don't claim to be 100% right in all destinations but we do credit a travel agent's account with $5 for every duplicate hotel that they spot.
roomsXML - travel agents count on it.
*3-star & above; as on 30 Sep 2015