Hi
Simplyfying Satish's solution:
In jsp1 define <hidden name="source" value="jsp1">
In jsp21 define <hidden name="source" value="jsp2">
and following thing in servlets method
String redirect=request.getParameter("source");
if(redirect!=null && redirect.equals("jsp1"))
redirect where ever you want
else
if(redirect!=null && redirect.equals("jsp2"))
again go where ever you like
hope this helps
Cheers
Praful