Ethical issues aside, this is a serious investment of resources for a scheme that I would expect is even less effective against the target than it would be against normal people.
Most of the time when we aiming at the question of a diffuse sense of self, we are talking about simulations of an individual. This is important, because the whole mechanism turns on the fact that as the simulation gets better, our confidence that we aren't the simulation gets weaker.
Cloning has no such mechanism. What you are proposing is like kidnapping and torturing one twin to get at the other, where the twins were separated at birth and had no prior relationship. Why would that work?
I think there's a lot more to be gained from using the necessary technology and resources in other ways. Sure, you could try to prevent people from robbing banks by nuking banks if someone tries to rob them - but it's a serious waste of resources.
In a close future, were we have enough technology to create a perfect copy of anybody using DNA, should we push criminals to surrender using a clone with the same memory, appearance ect by threatening them to punish or torture their clone ?
Or in the same way, torturing a perfect simulation of the criminal, until he surrenders ?
This would cause a serious ethical dilemma: should we judge the clone/simulation human, and could we punish/torture them while THEY have done nothing wrong ?