SURFSIDE, Fla.—About a block from the Miami-area beachfront condominium tower that collapsed sits its sister building, erected a year later by the same company, using the same materials and a similar design. It has faced the same tides and salty air. This has made some residents of Champlain Towers North worried enough to leave, though most have remained, saying they are confident their almost 40-year-old, 12-story building is better maintained. They say their building doesn’t have the same problems with cracking in support beams and in the pool area that 2018 engineering reports show the south tower had. The collapse of Champlain Towers South in the town of Surfside on Thursday has drawn attention to older high-rise buildings throughout South Florida and prompted Miami-Dade Mayor Daniella Levine Cava to order a 30-day audit of whether such buildings under her jurisdiction are complying with a required recertification of structural integrity at …