Custom PHP E-commerce cart E-mail Fix

Hello, We have site running here [login to view URL] if we add 5 items to cart and checkout the email is sent 5 times to a customer instead of 1 similarly if we buy with 3 different items the email of order is sent 3 times instead of 1 the number of products quantity price etc everything on order email is looking fine it is just that the email is sent multiple number of times depending on items we add to cart. We need some one to debug the issue its a php custom cart ftp access will be provided to selected programmer we will be choosing one shorty Please message us if needed any clarifications Thanks