HARRRIS WATERCOLOR

I MYSELF PURCHASED 4 HARRIS WATERCOLORS AT AN ESTATE SALE AND HAVING BEEN LOOKING FOR INFO ON THIS SAME ARTIST. THE PRINTS ALSO HAVE THE ND INC NY ON THE BACK AND THE SCENES LOOK LIKE SCENES FROM PARIS, BEAUTIFUL COLORS. MINE ARE FRAMED IN A BLACK THICK FRAME WITH A OLIVE GREEN TRIM, VERY FLATTERING TO THE WATERCOLORS THEMSELVES. THE #`S ON THE BACK ARE 1268,1268,1266,1265, MY QUESTION IS THEY ARE ALL DIFFERENT BUT I THINK TWO HAVE THE SAME #. IS THAT POSSIBLE? I FEEL GREAT ABOUT MY PURCHASE I PAID 35,OO FOR ALL FOUR. DOES ANYONE KNOW WHAT THEY ARE WORTH OR HOW TO FIND OUT?
THANKS
AMY