How to prevent duplicates of products added to cart?

[timbreman]

I sell audio through my site and don't require duplicates of any one product to be added to the cart.
Currently if 1 product is added multiple times it only lists the product image once on the checkout page and gives a small indicator of the actual number at the top.

Is there a way to disable duplicates of products from being added to the cart?
This has happened several times. Luckily nobody has complained or mentioned anything and I'm certainly not complaining about the additional funds received but I could see this potentially being an issue at some point.

Thanks,

[DrByte]

Have you tried setting the maximum to 1?
And/or check the radio-button to disable the quantity button so only 1 can be added. Combined with the maximum, might accomplish your goal.

[timbreman]

Have you tried setting the maximum to 1?
And/or check the radio-button to disable the quantity button so only 1 can be added. Combined with the maximum, might accomplish your goal.

Those options sound like they might do it!
Where can I find these options in admin?

[timbreman]

Have you tried setting the maximum to 1?
And/or check the radio-button to disable the quantity button so only 1 can be added. Combined with the maximum, might accomplish your goal.

I've looked through all the maximum options and don't see what you're referring to.
Also the only option I see for quantity is simply not displaying quantity. Quantity also only pertains to the number of products in stock not how many can be added to the cart.

[frank18]

I've looked through all the maximum options and don't see what you're referring to.
Also the only option I see for quantity is simply not displaying quantity. Quantity also only pertains to the number of products in stock not how many can be added to the cart.

In admin navigate to the product(s) you want to limit. Open the products page and you will see this:

Product Qty Maximum: (default is set at 0)

Set this to 1 and Bob's your Uncle !