Are you sure? Have you done this before, I mean have you loaded 2 different NOW accounts this way.
Because in my opinion double clicking NOW icon, which is NOW.exe, is as good as loading NOW by double clicking NOW.exe from any source say Zerodha portal or NOW portal. (Why do we need to copy NOW folder to D drive.) and by double clicking NOW.exe of D drive, it will load in C:\program files by default and not in D drive and this is not possible as you already has NOW in C drive.
Please confirm.