It should not happen, but we all err at some point. I know even the best pilots have made mistakes, and cockpit design should be focused on reducing or eliminating anything that can be misidentified. I know of a number of unintentional feathers, one where a crew was activating a fuel pump due to a failed auto switch, where directly above is the manual feather selector (backup for the feather through the CL movement), they went slow, and even identified the PNFs hand was on the switch and proceeded to feather a live engine. The PF just identified that the PNFs hand was on 'a switch', not reading the switch lettering. The CVR sounded like it was methodical and deliberate as mentioned here, they just did not pick up the error until the prop feathered. At least in that case they realized immediately what went wrong and rectified it.