Have two players ever played twice on the same tournament in tennis?

Question

It sounds impossible, but I just noticed a very weird fact that caught my eye and interest.

Tomorrow (13th February) starts the main draw of ATP 500 Abn Amro World Tennis Tournament in Rotterdam.

However, the qualification of the tournament has already finished, where number 6 seeded player Aljaz Bedene beat Uzbek Denis Istomin in two sets 7-6(8) / 6-3

Now, after withdrawal from main draw of Roberto Bautista Agut Denis istomin took his place as an alternative/Lucky Loser. And surprisingly enough he plays against Aljaz Bedene in the first round of the tournament. Meaning, two players are playing twice the same tournament. Which is quite extraordinary in my opinion. Has it ever happened before?

Answer 1

Yes. In the 2015 ATP World Tour Finals, Roger Federer and Novak Djokovic played each other both in the round-robin stage (where Federer won 7-5, 6-2) and in the final (where Djokovic won 6-3, 6-4). I'm guessing some more examples could be found in other instances of the Finals.

Answer 2

I wouldn't say this is something that happens frequently, but it does happen on occasion when someone that loses in qualifying rounds ends up getting into the main draw as a lucky loser - like the scenario you described in your question. That's generally the only way it can happen - I can't think of another scenario that would allow it to occur, actually. Only the round-robin format can typically produce that and only the World Tour Finals use that format - everything else is single elimination.

The problem with finding out when this happened and which players it involved is that there is no publicly accessible database that has all of this information in it - your best bet would probably be the Tennis Abstract website.