Dear Sumant H.S.,
Welcome to CiteHR.com!
Yes, there is a difference between Original and Duplicate, which is very evident. Duplicate documents are issued in lieu of the Original if it is lost or destroyed. There is also a third category called a True Copy or Attested True copies, which are merely copies of the Original attested by an authorized person or a gazetted officer.
I hope this clears the matter for you once and for all.
Warm regards.