Dashboard shows a double charge for a single sale

[TMG]

Checking dashboard for today's sales I see that a sale of 4 items to one customer was charged twice within a couple of minutes. 

What happened is:

- one sale to the customer, card dipped, customer signed

- second sale to the same customer within 2 minutes, card dipped, customer signed

Dashboard record these two sales twice. We have no way of contacting the customer to see if she was charged twice as well. Also the ID transactions are different

[TMG]

Follow-up on my message:

- The charges for the 4 items as described above were correct. Specifically there was a charge for one item, then 2 minutes later a charge for 3 items. 

The problem was elsewhere:

In addition to the charged amount, Dashboard showed two cash transactions for the exact same 4 items, each transaction with its own ID number. In fact, no cash transaction occured for these items

What happened? I have no idea. I asked the sales person and he did not recall doing anything special though he probably did. Still it is quite alarming to know that it is so easy to mess up the system. I issued a cash refund for both transaction to eliminate the cash amount from the records.