For example, “flammable” and “inflammable” both describe an object that can easily catch on fire. I can also think of “ceased” and “deceased”, both of which can mean someone or something has been brought to an end.
edit: Some people are including words that can also mean its opposite (like sanction or table), those are cool too! The more weird words, the better!
They’re called “contranyms”. Easy to find examples once you know that
https://en.wikipedia.org/wiki/Contronym
No that’s different. A contronym is where the same single word has two opposing meaning. OP is asking for two separate words that sounds like they should be opposites but actually have the same meaning, like flammable and inflammable which both mean “can catch on fire”.