Are you referring to property tax classification, as in it moves you from residential to commercial, or are there income tax remifications?

. - I would suggest posting here on biggerpocket in the classifeds section, on real estate Facebook groups, and find some local agents/wholesalers.Make the downpayment and interest whatever you want based on your current needs. 

Just wondering if property owners here retain property tax consultants or attorneys to help fight increased assessments, classification changes, or other issues with their property?

Didn't I just see a proposal that would change STR classification so that they will have to pay 4x in property tax?

This type of classification is identical to that of a vehicle.

This would avoid the $800+ LLC fee so long as you can avoid the classification of "doing business" within California.

Would these sites knowingly misrepresent the home's true classification?

It has nothing to do with commercial classification for realtor purposes. 

To begin, investors, lenders and brokers have developed property classifications to make it easier to communicate amongst themselves about the quality and rating of a property quickly.

It often depends on the definition of the zoning classifications within each city; based on the below info, I'm not sure which zoning classification a duplex would fall into.