Some lenders offer creative solutions, like a cross-collateralized loan, where they use your existing equity as security without refinancing the duplex.Another idea is partnering with private lenders or exploring a second-position mortgage, depending on your lender's terms.

Before I order a second appraisal, I would investigate an alternative lender.  

@Dan GroveAs a private money lender I agree with Nicholas' sentiment.

Since my firm is an investor private client boutique, I do not share resources outside of my client base.

Also, a few private lenders or hard money lenders might have some more creative terms for multifamily, especially if you're open to considering that route.

In your situation, I might investigate further to see if their credit was better before these hurricanes.

I first got started in real estate investing working for a real estate private equity firm in NYC.

I'm in a number of social groups for private lenders and have run into a lot of scams.

If you are tight on cash, then you want to use the lender that has the least up front charges to minimize your contribution.When I need to close fact I use private money.

Like @Chris Seveney said, private lending is a great way to go as well.