Use Bid Cache

Prebid.js currently allows for caching and reusing bids in a very narrowly defined scope. However, if you’d like, you can disable this feature and prevent Prebid.js from using anything but the latest bids for a given auction.

This option is available in version 1.39 as true-by-default and became false-by-default as of Prebid.js 2.0. If you want to use this feature in 2.0 and later, you'll need to set the value to true.

pbjs.setConfig({ useBidCache: true })