This commonly happens when you have a property that is deduped against more than one supplier. The cause of this is the underlying supplier response, and how iVectorOne dedupes them.

For example:

Search 1 - Suppliers used = Jumbo, Hotelbeds, Sunhotels

All 3 suppliers have the same hotel, but the Jumbo property is shown in the iVectorOne response as it is the cheapest for the property (iVectorOne is deduping by cheapest meal basis in this instance). The other supplier results are discarded.

Search 2 - Same criteria and suppliers used as search 1

All 3 suppliers have the same hotel but this time, Jumbo doesn't return a result (it may have timed out, or there could have been an error stopping Jumbo from returning a result for example). Hotelbeds is returned via ivectorone instead as it's the next cheapest.