Charging system oddball

Have a 51 Champion in the shop that had weird things going on with the charging system. Pulled the generator and found the thing had a twelve volt field coil in it...and the rebuilder had stamped "12 volt" on it. Almost didn't notice for all the paint, but saw some faint writing and started scraping paint and found his "marks". I recon he was trying to boost the output? New one on me although my local electric shop (in business for 45 years) said he has seen it before but not for a long time and also said it doesn't work real well and sometimes murders the regulator. Anyone else seen this before? Studebaker George