I presume you're referring to the fact that clicking "Exit game?" in the menu brings up a confirmation dialogue box with the exact same string? I agree, splitting that into two separate strings would be beneficial. I don't think the button in the main menu should have a question mark at the end. After all, none of the other buttons do, but if exit game is a question, they can be too. The question mark also looks awkward. The exit game confirmation string could then have a proper question (such as "Are you sure you want to exit the current game?"). Perhaps we could also rearrange the order of the options on the menu: rename "cancel" to be "return to game" and put it at the top, with "exit game" at the bottom.
At any rate, this isn't really a bug, but a feature request, so I moved it to the corresponding board.