Adam could choose how powerful he wanted the clone that he produced with his Unique Clone Skill to be, just like he could do with the Unique Collector Skill.
In essence, the summoning part of the Unique Collector Skill and Unique Clone Skill were the same. The cultivation level of the clone or summon would depend on how much energy Adam used to produce them and how much energy he used each minute to sustain them.
Since his clones would only be studying, Adam made it a rank one Novice Cultivator, and that only required him to use one IESP to summon it along with 1 IESP each minute.
That wasn't much to Adam and he could train for a few hours without pushing his body too much, then would stop to recover his energy storages, so that his clone wouldn't be retracted.
That allowed him to sustain the clone for very long periods of time and made it so that he would have double the results and could do two things at once.