PowerCollections 库具有类 OrderedMultiDictionary 基本上类似于 SortedDictionary< TKey，TValue> ，但允许重复。当你查找一个键，你得到一个枚举而不是一个单一的值。

The PowerCollections library has a class called OrderedMultiDictionary<TKey, TValue> that is basically like a SortedDictionary<TKey, TValue> but allows duplicates. When you lookup a key, you get an enumerable instead of a single value.

库是免费的，你应该能够做到你想要的类 - 将值存储为键。

The library is free and you should be able to do exactly what you want with that class - store the values as the keys.