specifying same column more than once in order by in spark sql returns different result when same column specified once in order

Question

q1:  select distinct y.c1,y.c2,y.c6,
    y.c3,y.c5
    max(case when  y.c3 is null and y.c4=\'N\'  and y.c5 <>\'Cancelled\' and p.c6 is not null 
    then \'Y\' el