While Kahn used his hack of using the doppelgangers to advance and perfect his fighting skills, magic, space law and blacksmithing skills at the same time. He had to pay greatly for it.
Since the original body, mind and soul was the main factor that linked all the doppelgangers… it was the one actually bearing the pressure of everything since the original Kahn was the anchor that connected them through the soul connection.
So in simple words… There were 16 Kahn existing at the same time. Each one doing their part and sharing the experience, knowledge, mastery, proficiency, physical movements and thought process.
And the original body was the one enduring all of it at the same time through sheer willpower alone.
Just imagine yourself hearing the thoughts, forcefully splitting your mind and focusing on different things at once while experiencing everything they were going through via a mind and body that wasn't your own.