This would not be possible with a duplex as the city recognizes that as a separate unit.

I develop all my own software with MS Access 2003 and I develop separate applications for every task.

As I said, only separates those who can or can't problem solve.

Are there any standard addendums or separate agreements that cover couples?

Or should I set on a final sale price and a separate lease agreement for the monthly rent?  

I have paid for appraisal 2 separate times, and had the money returned to me, and put in requests with 4 other appraisers, still no luck.

Where I come from, rents on the first floor and 2nd floor used to always be less than the first floor.Run your rentals exactly like a business should be run and leave the love, emotions and crazy thoughts out of your decisions. 

A side note is always based your deals off of the numbers not your emotions.

I have a detached bungalow house in the Castledowns area with two separate units.

The short answer is a duet is a duplex that is titled so that each side of the duplex can be sold separately.