^^In the weekly ranking lists on the ATP website players on the same points share the same ranking number.
That's why I was unsure whether there's any tiebreaks.
So, thanks for the clarification.
Apparently they just intend to keep things simple on their website.
It is because you were looking at the "Singles Race to London Ranking " http://www.atpworldtour.com/Rankings/YTD-Singles.aspx
. On the 52 weeks ranking they are separated http://www.atpworldtour.com/Rankings/Singles.aspx
all the players tied in the "Singles Race to London" have no chance to qualify to World Tour Finals so no real use to separate them