C++ feature, like std::set, which allows duplicates

Question

I have an std::set, which stores std::pairs of two integers. The std::set is also sorted, by allowing me to pass a helping class. However, I have written many lines of code so far and now, at the last tests, "they" told me something, that actually means that I need to allow possible duplicates in the std::set. Of course this isn't done with std::set. Any alternative that will not make me change the whole-big project?

In short, I use the std::set as an ordered list with data an std::pair of two ints.

Answer 1

You can use std::multiset. That should work for what you are describing.

Answer 2

std::multiset is the answer, as suggested by WhozCraig.