Deal with presentation being repeated in measure breakdown
Deal with presentation being repeated in measure breakdown

This was due to the DMD table sometimes having multiple entries for a
single BNF code.

annapowellsmith/openpresc,ebmdatalab/openprescribing,annapowellsmith/openpresc,annapowellsmith/openpresc,ebmdatalab/openprescribing,ebmdatalab/openprescribing,annapowellsmith/openpresc,ebmdatalab/openprescribing