@Michael VerniceThere's no single right or wrong answer to this other than IMO building a spec home is more involved than doing a flip. 

Would you invest in multiple single family units or try to find a multi unit property and acquire more doors all at once?

Is it a multi family or Single Family?

@Jacob BassettNo single answer to thatStart by reading this https://www.biggerpockets.com/real-estate-investin...You need to decide for yourself based on your own skills, background, network and capital as to what is best for you in your market. 

A single family home in a B neighborhood for 100-150k price range is probably more reasonable.

People from the around the world want to invest here (especially in multi-family), and inventory is extremely low across all types of real estate, especially single family homes. 

I found a potential deal that consists of the following: two 2 bed 1 bath single family houses on the same lot, but they have different addresses and separate utility meters.

Do this for every advertisement because they will steal pictures from Zillow or Trulia and create fake Craigslist ads, also.I started watermarking my photos years ago and haven't had a single fake ad since.

Because all five properties have one single mortgage.

You see, I would like to buy a single-family home to rent out.