SQLite 3.27

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create table t (id int, name1 varchar(50), name2 varchar(50), name3 varchar(50));

 insert into t values (1, 'Hans','Peter','Frank'),
 (2, 'Hans','Frank','Peter'),
 (3, 'Hans','Peter','Frank'),
 (4, 'Paul','Peter','Hans');
select * from t;


id
name1
name2
name3


1
Hans
Peter
Frank

2
Hans
Frank
Peter

3
Hans
Peter
Frank

4
Paul
Peter
Hans


with cte as (
select Duplicates, name1, name2, name3, row_number() over(partition by Duplicates order by name1,name2,name3) Seq
from (
 select count(*) over(partition by allnames) Duplicates, name1, name2, name3
 from t
 left join (
 select Id, group_concat(Dname) allNames
 from (
   select Id, Dname, row_number() over (partition by Id order by Dname) seq
		from (
			select id, name1 Dname from t union all
			select id, name2 from t union all
			select id, name3 from t
		)x
 )x
 group by Id
 order by seq
 )d on d.id=t.id
)d
)
select Duplicates, name1, name2, name3
from cte
where duplicates>1 and seq=1


Duplicates
name1
name2
name3


3
Hans
Frank
Peter