On a Monday morning in July, something new greetedCity commuters. In the space of one weekend, 12 Dunkin' Donuts stores and one Dunkin' cart had turned into new locations for the Canadian chain best known for its homemade doughnuts, Tim Hortons Inc. The move to open Tim Hortons stores in the former Dunkin' locations wasn't without some controversy. The Riese Organization had a franchise relationship with Dunkin' beginning in 1983, but the relationship turned sour several years ago. Dunkin', owned by Canton, Mass.-based Dunkin' Brands Inc., at one point accused Riese of not maintaining the locations. The firm initiated a lawsuit in 2002 to terminate the franchise agreements. Riese said it wasn't making any money because Dunkin' demanded Riese invest too much. Both sides eventually wanted to end the relationship and agreed in 2004 to sever ties this July.