In order that it would be possible to do the analysis, create a circuit with the desired DBMS on the website sqlfiddle.com
and left a link to his scheme, then we'll see. In a preliminary analysis, see that the question of categories in MYSQL since I did not work with this DBMS, that will try to write a sample simple SQL and something like MYSQL.
1) Simple and readable option:
select t.* from fitness.pair_sports t where exists ( select t2.fio from fitness.pair_sports t2 where t2.fio = t.fio group by t2.fio having count(*) > 1 );
2) What is muddy may work
select * from ( select @rownum:= case when t.fio <> @name then 0 else 1 end as rn, @name:=t.fio as name, t.* fitness.pair_sports t order by t.fio ) tt where tt.rn = 1;