Dear Alec Bramlett,
If there is a stacking restriction, the website will give you a notice when you add the items in your shopping cart. The website should also show you what you would be getting and a detailed description of the charges and discounts, right before you submit the order (Review Order section). It also depends on weather the promotion is a combo or a free item.
Please email us to Wecare@newegg.com if you still require assistance with this inquiry. We will be happy to help!
Newegg Support