Ah-hah! Sorry, life don't work that way

as soon as even a teeny tiniest amount of time passes, they are no longer identical. And for someone to marry and/or commit a crime, time
has to pass. No time, no action.
And even if no time passes, one will be created in a different location from the first. There you have it. Distinction, again. Even if the two
think they are identical, they
will not be.
Assuming we're considering an impossible
what-if case in a place where two clones
can be identical even though time moves on, then I suggest we use our clone-o-detectomat, which works with 100% accuracy and is powered by unicorns. Yes, I totally made that up, but hey - who started it?
Sorry if I come across as flippant. I may have missed some obvious point along this thread and am willing to be enlightened.
For the purpose of the OP, the "eternal life by cloning" is more of "someone very similar to me can go on with my work and life, but I'll still be writhing in agony over here until I die."*
*) about 75% of causes of death are neither fast nor pleasant. 9 out of 10 people will die in a hospital and not pass away peacefully in their sleep. Deal with it.