Thoughts on buying a duplex that's been converted to a 4 unit?

[Jeb Brilliant]

Hi All,

I'm looking at a duplex that has been converted into a fourplex. What are your thoughts on buying something like this? Specifically is it a bad idea to purchase something that has been converted? Are there foreseeable problems? I'm in the process of checking to see if it's a legal 4plex. 

One of my mentors is not keen on this kind of thing but I can't let it go just yet. The price is right and the rents are solid with year leases on everybody. I'm doing the due diligence but just keep coming back to the fact that it was built to be a double not a quad. 

So what do you think??? 

Thanks in advance.