I've seen it in a number of shows, but one that most easily comes to mind was an episode of Farscape where a ship with such a machine saw its inhabitants degrade into deformed savages. And though it wasn't copying and cloning per se, Crichton's 'Timeline' used that concept whenever the people involved were transported through time via their quantum machine. The more they did it the more 'errors' were seen and were cumulative, to the point where for one character they were in a way 'stuck' in the past b/c they knew one more trip would likely kill them.