Hang on, to shut an engine down we follow a set procedure of diagnosis, agreement of the condition, and then a monitored and confirmed drill with both pilots fully involved. If this is done properly then the chances of shutting down the wrong engine are extremely small. The thrust lever is retarded first, then the fuel control switch cutoff, then the fire switch if necessary. Each one is done carefully and deliberately and I always check that the other engine is still running at (usually higher thrust) after closing the thrust lever, and before moving the fuel control switch. Just a quick glance. I’d be even more careful for real I think, especially if both engines were at idle in the descent.