Single Listing Restriction (SLR) controls the behavior of campaigns of an advertising account among each other. It determines the maximum number of simultaneously delivered ads per ad request per advertising account.
If the SLR option is active, only one ad is selected per ad request per placement per advertising account, even if several ads, from different campaigns are eligible. In this case, only one will be selected for competing campaigns.
If the SLR option is disabled, multiple ads can be played simultaneously. This can increase the total volume.
By default, this option is active. If the option is disabled, several identical ads from different campaigns might be shown to the user at the same time.
If the advertiser promotes different sites from the same account and the ads differ sufficiently from each other, this option can be deactivated on request.