I'm doing correlations on school leaving scores and University scores. I use top_n to clean the school scores of retakes, but sometimes the poor candidate gets the same score on retake. How to eliminate these duplicates ?

  Studno  Math
      
 1 2105234    53
 2 2126745    10
 3 2126745    10
 4 2110897    41
 5 2344567    55
 6 2213467    63
 7 2314521    67
 8 2314521    40
 9 2123456    18
10 2123456    45

   duppymat1 %>% group_by ("Studno") %>% top_n(1,"Math")

This eliminates the two duplicates where scores are different, but how to code to eliminate one of the two that are equal ?