Two fires in Dorchester on Sunday evening caused $425,000 in damage and displaced one family, according to Boston fire officials. A two-alarm fire broke out on Hancock Street in a vacant 3½-story home around 5 p.m., said Steve MacDonald, a Boston Fire Department spokesman. No one was hurt, but the blaze caused $350,000 worth of damage, MacDonald said. The cause is under investigation, MacDonald said. As that fire wound down, another one broke out 3 miles away at a single-family residence on Gallivan Boulevard, MacDonald said. The blaze there was caused by unattended incense in the attic and caused about $75,000 in damage, he said. Although there were no injuries, the family was displaced and will need to fix the scorched remains of the attic before moving back in, MacDonald said.