The phrase is the same, except that the gender of the adjective are changed from neutral to masculine/feminine. This way, the verb "to do" applies to human beings rather than to things (see plures here and pauciores here).
In the context of economics, what is being employed is workers. Economic liberalism puts efficiency as one of its top values, so using the resources available in its optimal fashion is primordial to it. Thus, whereas the first quote represents a philosophical position known as Occam's razor, the new one represents a core tenant of liberal economics.
Finally, regarding the translation of the sentences, notice first that William of Ockham might have been the first to formulate it in such form, albeit using frustra rather than inutile. Such phrase (minding the modification) has been translated as
It is useless to do with more things that which can be done with fewer things
Notice that in Latin the noun "things" is implicit. However, as draconis suggested, this is better explicit in English, to differentiate it from the second phrase, which is:
It is useless to do with more people that which can be done with fewer people
Again, "people" is implicit in Latin, but need to be made explicit in English, to differentiate it from the above. Notice the plural remains though, since the number of the adjectives has not been changed. This is, using person rather than people would be wrong.
PS: I do not know if Leibniz actually wrote this, but it seems this principle goes back at least to Aristotle.