On the Settings screen, when clicking a button that leads to another screen AND there's a slider on the next screen in the same position as the mouse, the click sound effect will play twice. 

This may have to do with the new ability to highlight buttons by clicking them, although the slider doesn't seem to be getting highlighted on that click, as neither their text becomes yellow, nor can they be changed with the arrow keys.

The only screens affected by this bug are Music & Sound (mouse lands on the Blocks slider) and Chat Settings (mouse lands over Unfocused Height).

Additionally, notice that, if you click on the very edge of these buttons and quickly move the mouse away, in such a manner that they DON'T touch the slider on the next screen at all, the sound will only play once.