Shutter clicks twice

See, told yer (4th post from the top). So do I get a prize then, do I, do I?

Sounds like a bit of 'bounce' creeping through. Most mechanical switches 'bounce' a bit at times - ie make a number of very fast sucessive connections at first when operated. This is normally compensated for electronically (it just needs a capacitor across the switch really) - so it sounds like there is a slight fault there - more likely in the 'debounce' circuit than in the button itself.