Can I buy Medikinet 20 mg instead of 10 mg at the pharmacy?

Hi I have a question pharmacies on duty do not answer and I have medicines that I take chronically min Medikinet 10mg 2 times a day, but unfortunately I know that one pharmacy drużujaca that does not respond has this drug, but at a dose of 20 mg if I could because I have prescribed 4 packages buy 2 packages? I have been taking this drug for over a year and not taking in the world has led me to such mental stress associated with hyperactivity that I would like to finally be able to focus