Problem Multiple upload with iframe

I implement multiple upload with only iframe. Each upload occur only
the previous upload is finished or no current upload is taken place.
Each file upload has its own form. All form has “target” attribute
reference to an iframe in my page. It was successful, but there is a
big problem with the browser history. When I click back browser
button, it will upload the last file that I already uploaded. Do all
of you have a trick related to how to manage browser history or is
there any ways to upload with iframe without adding to browser’s
history? Or do you guys have any ideas? Always appreciate with your