For multiple mysql instance , fresh download required when one exist?
What i did is :

       i used existing my.cnf file and copy it in another location and edit
       some part of it :

         1. Commented #port=3306
         2. Added these lines at the end.
           [mysqld1]
           basedir ="C:\Program Files (x86)\MySQL\MySQL Server 5.6"
           port = 3307
           enable-named-pipe
           socket = mypipe1

           [mysqld2] 
           basedir ="C:\Program Files (x86)\MySQL\MySQL Server 5.6"
           port = 3308
           enable-named-pipe
           socket = mypipe2