Yuvraaj's secret accordin to me would be somewhat like this ' real yuvraaj may be raj or anybody else and he (real one) must have been a doctor and had been posted in sanjeevni as one of the interns but this yuvraaj must have taken his place (dont know how, may be by cheating) to take revenge from dr. shashank,this yuvraaj too (fake one) must be a doctor, otherwise he wont be treating the patients, he (may be) had been posted to other hospital but has taken place of the real one, to take revenge.