Let me share some understanding on the concept of parallel universe.
Remeber the episode where Dr Charak takes 'Eklavya' to the times of Mahaguru. At that time he asks him to firmly believe that parallel universes exists.
Now what does he mean when he says this.
Parallel universe means that whatever world we are living in at present, the similar world exists somewhere else as well but at a different time frame. So effectivey your different versions exists in different universes. Yo can time travel and meet your own past or future. Due to the existence of so many different parallel universes it is said that universe is infinite.
So Dr Charak took Eklavya at a time where he was young and studying in the ashram of Mahaguru.
Here only Asth saw Eklavya for the first time. And this is the reason he identified and attacked him in future at the very beginning of the serial. Remember Eklavya going to Dr Charak and tried attacking him and Dr Charak freezed him and identified that this is due to Beej mantra but the only person knowing Beej Mantra has already died.