Philadelphia Triplex Zoing - Legal Advice Needed

Hi,

I'm negotiating on a property in Philadelphia. My agent and I are struggling to understand the zoning rules here. The MLS listing says that the lot is zoned as RSA5, but my agent has reached out the city and the buyer's broker who have interpreted this zoning as being applicable to 3-unit buildings.

FYI - The property has already already been broken up into 3 units (with separate meters) by the seller.

For all of the experienced investors and attorneys in the Philadelphia area, can you provide some insights? Should I be worried that I'm purchasing a property that's not zoned correctly? Is this common in Philly (I'm new to the area)? And how can we determine (formally) if this property has been granted a variance for multi-family use?