Does a Lesser Simulacrum know it's a simulacrum, and if so: is there any reason it wouldn't run off and go do the things people do, when they have less than 24h to live?
And if it doesn't know, does it think it's its original?
It knows who created it, but it controls its own actions. It probably would go do whatever it wanted, unless given very good reasons not to.
I imagine the point of the spell is essentially to create a decoy, allowing the original to go elsewhere while people believe he's still around (or allowing you to abduct the original without anyone noticing for 24 hours).
(I wonder why lesser simulacrum isn't under its creator's absolute control, like a "normal" simulacrum is).
It knows who created it, but it controls its own actions. It probably would go do whatever it wanted, unless given very good reasons not to.That's what I think too, but it makes the spell so utterly useless.
I imagine the point of the spell is essentially to create a decoy, allowing the original to go elsewhere while people believe he's still around
A copy of a hostile creature will still be hostile, and uninclined to "hold the fort" for you. In fact, I imagine most non-good, non-lawful creatures will go on a nihilistic rampage once they realise their clock is running and there will be no meaningful reward or punishment waiting for them. Or become catatonic.
Even a copy of your own PC might decide to go watch its only ever sunset, instead of saving the world. Lesser Simulacra of people with zeal, like priests and (anti-)Paladins may choose to perform their duties to the end, but being bereft of magical abilities they're not very useful. Trained animals would obey you, but their originals are cheaper and more durable. Maybe if Simulacra knew all the secrets of their original there'd be a purpose to a cheap one, but that would just "break the campaign" instead.
"Expendable people" could have their uses, but when they take an hour to make, last less then a day and aren't obliged to take your orders, their only conceivable use is abuse. :p