I'm not sure how you would do that using Putty alone but if I'm not mistaking Putty Connection Manager, as reference here
has that option. If not you could have a look at Putty Command Sender
. As with everything have a look at Google first, that's how I found, as Linux user, a possible answer to your question.
Also, I'm reporting this thread to be moved to General since it's not Linux related in my opinion. You're looking for a way to execute the same command on several Putty sessions at once which would be pretty easy using Linux.
-- EDIT --
I'm sorry, I think I misunderstood you completely. Can you confirm that you have a Putty session from your Windows machine to a Linux server and are running that script/command(s) from that server? I assume since you're running over SSH that the server in question has no graphical environment, correct? If so, have a look at clusterssh
, it should be available in your repository.