Two TN's under two NAFTA occupations?

Question;

Has anyone here had or know of the liklihood of having an additional TN approved under a different occupation? Though currently working as an 'Horticulturist', could a 'Scientific Technician' TN be feasible for the second TN? I have worked under both categories in the past, though never concurrently.

Also; I found this on the USCIS Site; anyone familiar with this?

OFFICE OF BUSINESS LIAISON
U.S. DEPARTMENT OF HOMELAND SECURITY
U.S. CITIZENSHIP AND IMMIGRATION SERVICES
Employer Information Bulletin 11
U.S. Employment of Canadian and
Mexican Professionals under NAFTA
March 16, 2005

Change of TN Employment
TN-1 Canadians may change employers or add an employer by filing Form I-129 with the Nebraska Service Center or by departing the US and presenting revised documentation, relating to new employment, at the port of re-entry.