In google the ".." between two sets of numbers indicates search for numbers between the range of the two.
So, if Bing is trying to "emulate" google in that way for more advanced queries, they are doing it wrong.
Since google is sort of the defacto standard for search right now, I would say that Bing's response would be out of the ordinary for what a user accustomed to doing those kinds of searches would expect.
If the user entered "9999999..99999999999999999999999" in the search box, what would you say he desired to get in return?
Serious question, cause I have no clue about why would anyone genuinely want to search for that ...