Products quantity is doubled when added to shopping cart

When clicking to add a product to the shopping cart of my site it automatically doubles the quantity.

For example:

I add HTC Evo for 200.00 to my shopping cart. When I click view cart the page loads with the quantity automatically doubled (HTC Evo 2x at 400.00). The customers would have to adjust the quantity everytime they order products which can be a big pain.

Can anyone help me? Dont know where to start on this. I am using 1.4.9.4 and a custom template from readyman (simplered001) but am not sure if its a problem with the template or the actual coding in OC.

Thanks in advance for any help, cheers!

I helped someone with this before, it was due to the ajax add to cart AND doing a full post to the cart afterwards.

Can't help unless you provide a link though!!

That is exactly what i think is happening. It only happens when I click add to cart and not the little + sign next to the item title. But when I click on view cart it goes to x2. I will send you a PM as to keep the site private (for client) and later post the solution on here for others with a similar problem.

I thank you jcsmithy for helping me.

Did you find a solution for this ?