That one's easy. Beware an evil clone of you could be lurking anywhere, waiting for the right time to strike!

Exactly. And that's the point. The last two films made by Berman
Insurrection and
Nemesis what 'life lesson,' did we learn:
Insurrection: The federation is guided by morons. They give up the opportunity to cure virtually every illness including old age itself because 900 people don't want move.
Let's put that in a modern perspective. Let say the cure for cancer was in some South American tribal rainforest village and to cure cancer for the entire population we refuse to move 900 people. That's patently absurd.
Nemesis: The crew of the Enterprise are easily fooled by a effete French runway model that is allegedly Picard in his youth after the entire Romulan Senate is killed off.