I need to 3 copy for each invoice. I want to mention 1st copy - original copy, 2nd copy- dublicate copy and 3rd copy - triplicate copy. How ?

Write original , duplicate ,triplicate,etc on th header of the report and on the checking of the counter while generating the report the header will change accordingly. like for 1 it will generate original 2 duplicate,and so on 

By passing a string as parameter to the report & changing the text according to the string.