Does it make more sense to leave as a single family or convert to a duplex? The reason I am asking this, is it already has a second kitchen in the bottom level. It is a split entry if that makes any difference. 

This deal is about to begin its rehab and I am not quiet sure what the best approach would be here?

Any help would be great because this is currently my second deal that I am working on.

Thanks in advance

Do you have nearby, similar duplexes that you can use as a comparison?  If it were me I would start with analyzing the difference in rental income of a duplex vs single family.  This of course is assuming you are using this asset as a rental.  

It depends what you want to do with it. Are you going to be living in the space? If so, converting to a duplex may be beneficial. A duplex could also minimize the impact of vacancies if only one unit is empty. 

If you are not living on the property, I think it really just comes down to how much rent you could get for 2 separate units with X amount of bedrooms as opposed to a larger SFH. Look at your local market and see which would yield more cash flow.

In my opinion, there is no reason to waste money converting the property into a duplex if leaving it as a SFH would cash flow the exact same or better.