Alice believes that Bob's team won that day's round-robin tournament.
What might she think about this statement:
2. Bob's team won that day's bonspiel.
As you've guessed, "bonspiel" is simply curling jargon for "tournament." So Alice believes that Bob's team won that day's bonspiel.
Now, if she doesn't know what "bonspiel" means, she might say she doesn't believe Bob's team won that day's bonspiel. She might even insist on denying it: "No, they won the tournament. If they had won the bonspiel, too, Bob would have told me." In this case, her belief -- the thing she accepts as true based on what Bob said -- is correct, but she has somehow formed a false opinion about the term "bonspiel," which causes her to form a false opinion about the meaning (and therefore the truth) of Statement #2. If the meaning of #2 were made clear to her, she would necessarily have to admit her belief that it is true.
What I'm intending to suggest here is that different statements can have an identical (for practical purposes; again, I'm not constructing formalisms) meaning; that if someone is aware that two statements have an identical meaning, he can't think one is true and the other is false; and that if someone is not aware that two statements have an identical meaning, he can think one is true and the other false without necessarily being wrong about whether what they both mean is true.