It would be so helpful if when you created a similar item, the ASIN field would be blank instead of retaining the old data. It's kind of a pain if you forget to erase that old ASIN and it attached itself in the Amazon system to the new product. Due to the delay in the item showing up in Amazon, it's a lengthy process and easy to forget to remove it when it shows up incorrectly in Amazon.
This has been added to our roadmap. When I have further information I will update this request.