I'm racking my brain to understand this, mostly because of the "but"-part.
Sure, fair and equal are different concepts. Sometimes, it may not be fair to treat different groups equally.
Could you give an example of a "fair but equal" situation?
I browsed for examples and in most of them I don't really see a sophisticated ethical concept (it might as well be "fair and equal" or just equal or just fair; maybe the original meaning got lost). For example:
- Costa Rica, a team the United States considers a fair but equal opponent in CONCACAF play.
- settlements in a divorce must be fair but equal.
- Can I receive fair but equal justice in court without an attorney?