Official documentation sent out by Valve (the company behind the Steam platform) to developers explains that moving forward, “with Steam Bundles, if a customer already [owns] some items in the Bundle, they will pay for and receive only the items not already in their account”. Valve further explains that “past Complete Packs were sometimes a bad deal for customers that already [owned] one or more of the products in the pack” and that players may have seen these as “bad economic sense” and so avoided buying them .
Some fans may have even felt like they were paying twice for content they already owned, says Valve, but these changes allow consumers to “complete the set” of games they’ve already started building. It will also let them get a good deal on the “remaining items in the Bundle”.
PCGamesN, which first reported on the Valve memo, also notes that the feature already appears to be in place. The Headup Games Complete Bundle is currently slashing the prices of many games from the German publisher, but, if the Steam user already owns a few of the games included, then some money is knocked off of the bundle price. Moreover, the big green bundle discount figure (which is automatically 75% if the user doesn’t own any of the games) also changes too.
Valve’s other recent changes to the Steam store and its policies also support the fact that this bundle discount feature may soon be rolled out on Steam store-wide. In the 2015 Winter Steam sale, Valve stopped asking developers and publishers for two discounts and instead asked them to list one discount for the duration of the sale in an effort to “optimize” the sale for customers. Some months ago, Valve also made it much easier for Steam users to request refunds too.
Source: PCGamesN, Steam