single vs. double field alternator?

65 225 dart, piecing it back together. oem would be single field alt., order total of 3 from bumper to bumper, all came double field, instead of single field,,,owner of store calls their tech and they say, " no big woop. just hook up THE,one field wire to the lower terminal", I ORDERED SINGLE FIELD ONE YESTERDAY FROM o ' REILY, THEY EVen had choice of 50 to 60 amp. question is is it good to have the correct single field alt for function or could a second field wire be added to the double field one????? i did order the 50 amp as it appears all these old cars had dash wiring troubles from what i read on the forum. just wondering. ( or as Mom said, " don't be thinkin, you're not used to it!!".