I just realised that my game is getting 2 WM_LBUTTONDOWN and WM_LBUTTONUP messages every time i press or release the mouse button. I noticed it when i was debugging and saw that a method that was getting called when the game was started was getting called twice. And this was because two consecutive mouse up events were being generated when i clicked the "Start" button. I am using SDL, and my own GUI system, but the messages are coming from Windows. I can see it in Winspector Spy. Two WM_LBUTTONDOWN messages when i press down, then two WM_LBUTTONUP messages when i release. But the funny thing is that when i click any other button it doesn't happen. I don't think i am sending any messages or anything like that, i am not calling SDL_PushEvent. Anyone have any idea what could be causing this?

I don't think so. What's a desktop accelerator?
Naturally, it isn't happening with any other programs' windows that i inspected. I suspect it could be something to do with SDL