SQL & PL/SQL :: Check If Multiple Column Values Are Same?

I have a table as follows

create table teststr (indname varchar2(20),
counter1 number,counter2 number,counter3 number,counter4 number);
insert into teststr values('a',10,20,30,30);
insert into teststr values('b',10,20,5,3);
insert into teststr values('c',2,4,5,2);
insert into teststr values('d',1,2,3,4);
insert into teststr values('e',4,5,4,4);

Now i need the output if any of the column values are same.

output should be

select indname from teststr where counter1=counter2
or counter1=counter3 or counter1=counter4
or counter2=counter3 or counter2=counter4
or counter3=counter4

a
c
e

Is ther any other way to write the query instead of the numerous or conditions if i want to compare the column values in a table.