Prevent Magento from Copying Product Images

I appologize if this has been asked before but I cannot find any solutions so I wanted to reach out for some help. We currently use Magento 1.9 and sell heating and cooling products. A lot of our products share the same product images (ie: same brand of air conditioner would all have the same image for 40 products). Whenever a product is duplicated in Magento the images are copied as well. Since the images for these products will be identical, is there any way that we can prevent Magento from copying the product image and instead use the same image for the new product? We run imports and duplicate some products by hand.

I am aware of plugins that will search for duplicate images but all the ones that I have seen look for any images that are upload and are not currently used and then removes the file. Ideally we want to have them all use the same file without any duplicate files.

Example

air-conditioner.jpg – all use this file

air-conditioner_2.jpg – prevent this image

I believe that the file for duplicating the product image is below but I am not sure what would need to be updated. I am aware of not editing this file directly.

app/code/core/Mage/Catalog/Model/Product/Attribute/Backend/Media.php