If you could give specifics of the building (layout, e.g. 5 room 2 bed) and pricing desired I might be able to provide you with more constructive opinions. 

Also I think the layout was kind of weird.

Even then, you have things you can't decipher without actually going through the property (bad/good floor plan, tiny/huge/awkward layout bathroom).

That was three years ago-the other half of the duplex is literally on the market right now for 300k - same layout, side by side duplex.

Also, make sure you lay out the specifics of the partnership so the roles and responsibilities are clear and please use a formal agreement. 3.

Perhaps the ideal layout to maximize the lot would be something like this image:My question is:  can I build 2 duplex's, one on each side facing the street ?

I have two options in front of me either to obtain a rehab loan, which will cost me $10k for six months ( points, fees, interest) or just finance the entire deal with my own money (cash).The rehab loan will enable me to obtain an additional property, so in six months i'll have two properties ( one with the loan, another with my cash)  but it'll cost me an extra $10k (on top of the regular down-payment which in any case i'll have to lay out) .

The layout is apartment style,  but they call it a condo.

Also the layouts, are they true 2-bedrooms or is a "bonus space" counting as a 2nd bedroom that almost nobody would use as such? 

After starting the project, the architect and OCD in me took over and I ended up changing the entire layout of the entire house and we went way over budget on electrical and plumbing because it was the right thing to do with the condition of things.