BRRR with already occupied units?

[Dakota Malone]

I'm looking to buy my first property and I have a duplex in front of me for sale 53k and both occupied for a total of $1,700 monthly. I'm waiting for a call back from the seller for actual details and comps being put together, but with high rental net and a low mortgage payment it seems I would be in for decent cash flow. I'm a little confused though, with both places occupied.. is rehabbing the exterior for a higher appraisal and keeping them both in leases the way to go? Should I rehab one side and keep the other tenant? 

I don't have any pictures of inside units yet but as far as I know there's no major problems with the house. I plan on buying a home and rehabbing out of pocket (10-15k). Does it make sense to keep the house with $1700 net while cleaning up the exterior for a higher appraisal, and then refinance after 6+ months? 

Thank you in advance