They can help you make decisions to achieve your end goals and objectives.  

First ask yourself Why did I buy the duplex in the first place:  What was I trying to achieve.  

Taking this route not only makes it easier on you, but also shows your tenants that you care about them and are willing to be flexible, but not taken advantage of.So my advice to you is to communicate with them an figure out how you can assist them, maybe help find them a new place to rent or find out what would motivate them to move out sooner (cash for keys, etc.)Hopefully this helps and please feel free to reach out if you have any questions!

If you prefer the formal process of going through a buyer's agent that early in the shopping process, let the agent know up front your timeline and your motivation or lack thereof for buying on that timeline. 

And keep up with the bigger pockets community to stay reminded of what you want to achieve. 

No one sending you a letter to buy your home has any other motivation but to make money for themselves everything else is just words and I am sure you understand that..

The key to either of them is to have targeted data of motivated or distressed sellers.

@Kevin PerksInstead of formulating whether you should do something or not, you should be talking with professionals telling them what you are looking to achieve and ask for their advice on how to achieve that.I talk with so many investors who go blindly into establishing an LLC who have it set up incorrectly.The worst part of having an LLC set up incorrectly is that you think you are getting liability protection...when you likely don't.Best to talk with an attorney on asset protection / LLC Formation.

The reason I ask about this is that I love the vacation STR strategy, but I know nothing about top-producing vacation markets and what is achievable.

I have no real expertise here though, although I have been a court mediator and am used to helping people lay out motivations, wants, needs.