When you see 100% or 200% extra on a deal, it's based on the amount of chips in the nearest standard store package. The amount posted in the offer is the amount that will be deposited when you complete your purchase.

For example, this 100% extra special offer of 300,000 chips for $1.99:

300,000 chips is 100% more than the standard store package of 150,000 for $1.99.

Here are the standard chip bundles in the store while there are no promotions running:

Most of the time the store will have promotional offers running. Promotional offers deposit more chips per dollar than the standard store packages, even if there is no 100% extra badge in the store. If we are having an in-game event, then we have chip promotions in the store. The amount of chips shown is the amount of chips that will be deposited upon purchase.