Keeping track of your Sticker Albums' progress is crucial to identify the stickers you will still need from events and/or purchases..
The game features three types of stickers: Common Sticker, Gold Sticker, and Super Sticker. It's important to note that a Guaranteed NEW Sticker of a specific type ensures only that type of sticker will be obtained.
For instance, if an event offers a Guaranteed New Common Sticker. Thus, you are expected to receive a Common Sticker and not a Gold Sticker. If you have already collected all the Common Stickers, you will receive a duplicate.
The same principle applies to Gold and Super Stickers.
For more information on how stickers work, we encourage and invite you to check our FAQ Article titled: Sticker-know-how.