Check bookkeeping query is on both magnet polarities (typical request)
It may happen that by mistake a bookkeeping query is only specified for a single magnet polarity whereas it is certainly unusual for a user to submit a request to run over a single polarity data set. A warning should be issued when such a request is made, to avoid surprises. This has happened as discussed in the AProds request lhcb-datapkg/AnalysisProductions!99 (merged).
Similarly, a check could be made that there aren't two identical productions with the same polarity, as happened here when the BK path wasn't changed within the loop. This should cause a pipeline failure.