paypal payments pro double charge

My client has told me that occasionally, they are receiving multiple orders with the same invoice AND these customers are being charged twice (even a third time on one occasion).

All of the sessions are cleared on a successful transaction, and the problem is intermittent

Can anyone advise on some checks I can make to try and pinpoint the problem ?

The issue seems similar to one where IE customers were getting trigger happy on add to cart button , resulting in the same item added to the cart 2 or 3 times, but this was resolved by modifying the 'if in cart' behavior, maybe unrelated, but a thought.

Thanks

It sounds like the customer is clicking the submit order button more than once on the confirm page.

Either put a note on the confirm page to only click once or you will be charged twice, or disable the submit button when it is clicked using javascript:
<input type="submit" name="button" id="button" value="Submit" onclick="this.disabled = true"/>

Thanks Jason,

Will give it a try.

you're welcome.