Though we have had some success duplicating the process in the laboratory, i t cannot be said the process is totally correct.
do i need an "in" before duplicating? why or why not?
You can add "in" if you like and if you don't, it is still understood. There are many sentences written like that. The most recent usage is , "The under-manned law enforcers didn't have much success (in) stopping the looters nor the snipers in New Orleans."