Incremental Publishing Edition picking up content items incorrectly

Hi, we have an issue where a number of incremental content lists we have set up for publishing images are picking up image content items that they shouldn’t be picking up and thus publishing images that havn’t changed and don’t need to be republished.

The content lists are set to “Incremental” and they are set to pick up images. We have two different images a normal “Image” content type and a “Gallery Image” content type. The normal “Images” are being picked up as expected when they have changed, the “Gallery Images” however are being picked up all the time, whether they have changed or not.

I’ve searched and the only issues I’ve found which were similar involved parent content items publishing out as related child content items had been amended. However obvioulsy these are binary images so they don’t contain slots with related content items in them.

When I preview the XML for these content lists the modified dates are long in the past for these images which are being picked up.

I’ve checked the template being published out template and the “publish” property is set to “default”.

This issues is really slowing our publishing down so any insight in to the cause of this issue would be appreciated.

We are running 6.5.2