AbleCommerce Shopping Cart Software

We have a site that experiencing the following issue.

On some orders(appears to be random orders, but limited to the same 2 products) the customer is being charged twice for shipping.

Here is what I know:

I have checked the products, and they appear to be the same as the others on the site that are not experiencing the issue.

The orders with double shipping only have the affected products in them.

All orders on the site that do not have the 2 affected products are only charged once for shipping.

We are using the single page checkout.

The only update that we have done since the site went live, is to add a <machineKey> to the web.config to resolve an issue we were having with users being logged out.

To my knowledge, there have not been any updates to the shipping methods on the site.

The shipping methods are all flat rate.


If anyone could help me resolve this issue or point me in the right direction, it would be greatly appreciated.

Thank you
Chris

Can you figure out if there is anything special with these products. For example if these both are kits, their warehouse settings etc. Secondly what are the shipping methods those are getting applied for such order? If you are using some shipping provider then what if its increasing the price due to product weight?

Thank you mazhar for the quick reply.

None of the affected products have kits associated with them.

At this point there appears to be 3 products that have had this happen.

I believe in all cases it is a single product that is ordered, but the quantity could be more than 1

The shipping method that seems to be affected is flat rate, "include handling fee in shipping cost", handling fee is not set, "all warehouses" (we only have 1), "all zones", "all groups", tax code is taxable(in our case a single tax type)

We have 3 shipping options on this site, all of which are configured the same way, but for different amounts. Only 1 of them seems to experience this intermittent problem.

We are not using a third party shipping provider, it is out of the box able commerce flat rate.