Just putting this here as a warning/reference since customer support resolved my issue within the game, but the canned response I got makes me wonder if the issue is fully understood for Battle.net
In Battle.net my library for Diablo 3 is showing that I am able to purchase a $25 upgrade to the Digital Deluxe version of Reaper of Souls. However I can still see in my account purchase history that I purchased this product on March 20th 2014.
I only became aware of this as I had not played since Season 33 and I went in to delete a old character in order to change their name for the new season. However once I deleted the character I was unable to create a new one as I no longer had enough empty character slots. I was able to create a support ticket and within an hour my 17 character slots are back available for me to use. Thank you for that support team.
All that being said within Battle.net it still allows me to repurchase digital content that I already own and I was getting annoyed to the part before I realized what happened that I almost did double purchase it. Putting this out there as a warning to others to double check that this didn’t happen to you.