My local grocery store is called "Gelson's", and i recently received an ad which included something to the effect of "Gelsons' goal is to.... etc." Is this correct? How do you make a possessive proper noun into a double possessive, of sorts? do you simply drop the initial apostrophe, as they did? surely you wouldn't say "Gelson's' goal", right? I'd defer to their expertise had the ad not been riddled with the it's/its mistake (YART).

TIA