No. Unfortunately, due to current system limitations, you can only apply one discount per order*.
If you accept an offer at checkout for a discounted coin (such as the one below) you cannot add a further Collector Club discount code prior to checkout, as the Collector Club discount code will override your offer discount and you will be charged full price for the item.
Offer popup example:
If you accept the offer displayed on the popup, your discount should apply, as below:
If you add your Collector Club discount code at checkout after accepting an offer, the new discount will override it and your offer item will no longer be discounted:
Note: If you accept offers across different brands, i.e. a Star Wars offer and a DC offer, only one offer item will be discounted, as we cannot combine discounts. We apologise for any further inconvenience.
*We hope to have this issue fixed in the new year.