I will admit that I didn't think of what Hypo said.

The Tollestia people made it look like Celestia purposly sent two tickets to Twilight knowing she had five friends, in order to cause a fight - hence Tollestia.

However, while it could have been an accient, I personally like to think she was trying to test out the firendship of the ponies. They're the holders elements right? The elements are at their strongest when their holders are friends (proved in Season 2). I think Celestia was giving them a very minor threat to their friendship in order to see whether they'd stay friends, because if they didn't then that would mean the wrong ponies were given the elements; if such a small problem could turn them against each other, then what would a series problem do?

Does that make sense? It could all be coincidence, but that's how I like to look at it.