Typically filler spots will NOT play back to back.  This usually only happens if a particular item is in inventory more than once.  Remember that Fill content can be of any type.  So, it’s possible to have the same element added to inventory multiple times.  This most commonly occurs when a station is using PSA’s as Fill items and then also using some of the same PSA’s for Target Spot Under-ads, or other Fill items.

The best solution to correct this issue is to add more items to a playable category either by manually uploading items, using the Bulk Upload Tool, or by adding items from PSA Wire.  You can also prevent back to back play by adding fill items to a Frequency Cap Family in addition to the Enable Family. 

If filler spots are playing back to back, please verify that each is in an "Ad Family" which has a frequency cap. You can go to Ad Families link of the station inventory screen and then select the spots in question.  Make sure you "add them" to a family which has a "Family Cap". This will prevent these spots from playing back to back. For more information see articles on PSA Wire, Bulk Upload Tool, Adding Fill Content.