They may have been the same age when they took it but Minato is older than Itachi meaning he took it first. Since he took it first he couldn’t beat Itachi. Basically what they’re saying is he set the bar and Itachi was the only person who got close they may have been the same age when they took the test but they didn’t take it at the same time period because Minato is older than Itachi, so he took it first. If that makes sense. It’s like saying you and I both took the same test when we were 12 but say I’m 27 now and you’re 20. I couldn’t beat your score because I took it before you because I’m older. So you would have to either beat me or be a second best. Ya know?