Authorize.Net duplicate transactions in Batch Events Shopping Cart

We are using Authorize.Net as a payment processor for Event Registrations AND using the shopping cart (yes I know the cart is "alpha code"). On the front-end everything looks and works great. Payments are being being processed correctly at Authorize.net and appear in the contact record as a payment for the correct amount for the event. However, in the back end, when looking at the Accounting Batches the payment amount displays 3 times with the first transaction showing the Trxn ID#, then twice more with the Trxn ID# appended with a "-1" (see attached screen shot from Demo.Civicrm.org). I set up my Authorize.Net developer account settings on Demo for anyone else to try out.