Issues after upgrading to 2.3.1

-- url of the page with the problem -- : www.bestpub.com/
-- HikaShop version -- : 2.3.1
-- Joomla version -- : 2.5.22
-- PHP version -- : 5.3.27
-- Browser(s) name and version -- : Many
-- Error-message(debug-mod must be tuned on) -- : n/a

After upgrading to 2.3.1 we have a couple problems we have been trying to debug.

First problem:

We had always received two emails for every order. One email was with the order details, and the other was the payment confirmation. We no longer receive the payment confirmation emails. We are using Authroize.net AIM as our payment gateway.

Any ideas why the payment confirmation emails have stopped?

Second problem:

This does not happen all the time, but enough so that it is an issue. When an customer is placing an order and in the checkout, they proceed and get an error that the credit card can't be processed (I am working on getting the exact message they receive), and the page refreshes letting them try again. So they try again, and this time they get a message saying Error #11 and something about there being a duplicate order.

On the backend we never see any orders come through from those people. I have not found a common OS/browser combination with this issue. I have our support folks trying to gather more information. At the moment though, I don't have any more to go on.

Has anyone ever seen anything like these issues? Anyone have any thoughts how to fix them?

Any help will be appreciated.
Thanks.

In regards to item 1, I took a look at that post, found the typo in the code and fixed it, however the problem still exists.

Any other thoughts on how to restore the payment confirmation emails?