Cart Merge, a Magento module
This module allows you to remove the merge between the customer's cart and the visitor's cart when the customer connects.
app directory recursively into your magento folder.
Usage: ./install.sh [un]install [magento dir]
System > Congiguration > Checkout, part
Shopping Cart Merge Options :
Disable Merge: Set it to yes if you want to disable the cart merge.
Clean if visitor's cart is empty: Set if to yes if you want to keep active the merge if the visitor's cart is empty.