Don't allow duplicate ids in multifetch request list (closes #2626)
Don't allow duplicate ids in multifetch request list
(closes #2626)

1ec5/iD,morray/iD,digidem/iD,kartta-labs/iD,AndreasHae/iD,digidem/iD,kepta/iD,1ec5/iD,morray/iD,tbicr/iD,ngageoint/hootenanny-ui,tbicr/iD,mapmeld/iD,AndreasHae/iD,bagage/iD,1ec5/iD,openstreetmap/iD,andreic-telenav/iD,mapmeld/iD,bagage/iD,mapmeld/iD,ngageoint/hootenanny-ui,edpop/iD,andreic-telenav/iD,kepta/iD,kartta-labs/iD,bagage/iD,zbycz/iD,openstreetmap/iD,ngageoint/hootenanny-ui,zbycz/iD,edpop/iD,openstreetmap/iD,kartta-labs/iD,edpop/iD,energiekollektiv/openmod.sh-id,energiekollektiv/openmod.sh-id,AndreasHae/iD