@Chris Jensen makes some fantastic points, so I would read his comments and then re-read the last three paragraphs until you are sure that you understand it. 

Sorry I just reread your comment and realized you don't yet own the duplex, my previous advice would be for properties you own!

Go back and reread what @Nathan G. said. 

But I just re-read your first post. 

At this moment, I'm re-reading it a second time.

have reread and highlighted things throughout the home study course over and over again....

Actually, Im so new I had to re-read half this thread just to follow the lingo!

(Now, I need to compensate my re-reading of this book with some real action finding a property, other than just scanning Loopnet.)

I just reread my post and I should clarify.

I was re-reading Multi-family millionaire book and in Chapter 19, Brandon's advice on checking building permits is to visit your local building department prior to closing to let them know that you're buying the property, and ask what outstanding permit issues or infrastructures may cause issues.In your case, it sounds like that the building department already knew about what permit issues exist on your property.