Alexander's Worldview (Part-1)
Alexander's reason for creating duplicating spy agencies could be described using a single sentence, 'Some spies are needed to spy on the spies.'
In this way, Alexander hoped that in the event of a rebellion, it would be very likely that plans of such treacherous actions will be leaked by spies within that spy agency, each ratting out the other for glory and honor.
This was the same case in his previous world, where all countries had multiple duplicative spy services that did very similar things and who were actively encouraged to compete for funding and favor.
For example, the USA had so many letter intelligence services, CIA, NSA, FBI, DIA, the list could go on, who did a lot of the same thing and thus could be much more efficient if everyone worked under one giant organization.
But then that organization might get too much power.