Buying my first duplex options

[Joshua Martin]

Hello all, I’m buying my first duplex and have been soaking up information with a firehose. But still blurry on some areas . Looking for some advice . I’m buying a duplex for 55k which bank has already given me go ahead for with 20% down and 4.5% either 15 year fixed or 30 year adjustable after 5 years. I also have enough money to pay cash for the place .

 Would I benefit from borrowing against my equity in my house to purchase it ? And then take a loan on the place ? 
if so what would be the advantages of that ? Or do I just do the 20%.