Here is my comment added into the Bugtracker where someone reported this issue with "add_date" field:
"My first advice to QT maintenance team for this issue is inserting a new field in [xcart_products] table called "update_date".
- add_date = date of product creation, this should remain always the same
- update_date = date when product information was updated
- (optional) avail_date = date when a new product starts being available (for coming soon module)
Modules like "The Newest Products" or customizations like "Sort by Date" depend of "add_date" field. As Tech Team reported there is an issue with this field. It is updated to current time after any modification in product data.
My second advice is letting shop administrator to change in back-end the "add_date" field. I already did it for you here:
http://forum.x-cart.com/showthread.php?t=63608&highlight=add_date
If someone wants to show them in front-end could use these values (add_date, update_date, avail_date) according to own needs. For example you can let your customers know in product page when the product was created or when product information was updated, or when it will be available (coming soon feature)."
So folks, we have a Program Logic issue here ...