I am working on Magento 1.9 CE and I want to know how multiple coupons are applicable for one order in onepage checkout. When user apply two coupons in checkout process new one coupon remove old one coupon, this is my problem. I want both coupons will work for one order. Please anybody help me about this problem. I will appreciate your help.
This extension can help you with this: http://www.magentocommerce.com/magento-connect/multiple-coupons-by-amasty.html
Thanks for your valuable reply, but I want to implement multiple coupons without any extension. If extension is free to download so I can use it. Please suggest me.