IE - Sendmail sends mail twice??????????

Hi all,
I got a strange problem with sendmail.
When i tried to invoke mail from web.appln(php+apache) using linux machine - it sents mails only once.But when we try to use IE in windows the same mail is sent twice :rolleyes:
I tried safari browser in windows it sends mail only once.
So what's the problem????I hope somebody will help me from sendmail headache :(
Any ideas to solve this issue???

It's solved . not a problem in sendmail.
Web site developers submitted the page twice(from java script they submited form twice)..so it's send mail twice from windows
and once from linux.:)
Seems to be problem with IE ..