IC 815 is not IC 3760, though some lists -- notably Adelaide Ames's Virgo Cluster catalogue of 1930 -- equate them. Frost has both objects in his list, and places them about 1.5 arcmin apart. His positions, however, are given with a precision of only an arcminute. So, the actual separation, just over an arcminute, is well within his nominal error, and the two galaxies are clearly separate objects. GSC includes them both, and I've listed them as separate objects in my tables.