If you get 100 upvotes on an question or answer, that'll get you a Great Question/Answer badge. Likewise, there's the Famous Question badge for question views. But what happens if you already have a Nice/Good Answer? Does the lower-level badge get replaced, or does it stay?
The description for the Nice Answer badge says:
This badge can be awarded multiple times.
You earn a new one each time you meet its requirements, for each answer that meets it. Your gold or silver badge never 'replaces' your bronze badge: you get it in addition. I still have a Nice Answer badge for each of my answers that also earned me a Good Answer badge, and both of those for the answers that gave me Great Answer badges.
If you click on your badges, you'll see which answers you earned them for.