Add to cart adds double products to the cart intermittently

[capewellmj]

Hello

We have noticed a bug on our virtuemart site that seems to have appeared since VM2.0.22.

When a customer adds something to their shopping cart it adds double what is in the quantity box. Then on the cart page the customer has to update the quantity twice in order to get it to display the correct quantity.

It never used to do this and it doesn't do it every time. Any ideas what is causing this?

We are currently using VM2.0.26 + Joomla 2.5.16.

Thank you,

Martin