Prices double at checkout Magento - sales_order_flat_quote_address

Question

We are currently experiencing an issue on Magento Community 1.7 where some customers have their totals doubled at checkout.

Investigation has shown that for these customers quotes, they have four entries in the sales_order_flat_quote_address table. This table looks like it should only contain two rows, one for billing and one for shipping.

We are stumped as to why four rows are being created and through vigorous testing cannot find the cause of the issue.

The following test cases have been completed without issue:

1) Create quote and then login. Logout. Create new quote and then login.

2) Ensure no previous quotes for customer. Login. Logout. Add products. Login.

3) Create quote while logged in. Leave logged in. Access seperate browser, add products, login with same customer account.

4) Create quote, login. Open site though proxy / new IP. Add products. Login.

In all the above instances, the issue does not happen.

Has anyone ever had or heard of this issue before?

Thanks in advance.

Answer 1

We had this issue on enterprise 1.12. It was very difficult to trace and we raised it with magento who provided a patch.

Are you using OneStepCheckout on your site? Or any other 3rd party modules?