Hah, a half-trick question.
YOU can know the truth before you know it is the truth.
So the answer to your question is a resounding yes.
I could say that "I know that my shoe size is 13" without checking what it actually is. I might believe that it is the case because I was size 12 before and feel that my feet have grown a little since then.
Only when I challenge my "knowledge" and I find out that I am indeed size 13 do I know it's the truth.
But it could be argued that my arrogant assumption, which was not based on any real evidence was after all the truth in the first place.
But that is to say that I was 100% certain of my shoe size before verifying that it was what I believed it to be.
I think that is a mental disorder.
To be certain of something you cannot be certain about is probably a mental disorder and so in answer to your question:
Yes, but only with people who are twisted enough to believe in something 100% with no basis for such a belief. (Any basis after all would have involved challenging).
Well, I hope that was in the least bit coherent, interesting question, thanks!