I have this formula:

```
=IF(testing!I:I=A6;testing!A:A;"wrong")

```

I want to control with the formula whether the mapping of values is right.  

I want to know whether the value in A6 has more corresponding values in the column A in the 'testing'-sheet. So when A6 appears in the column I, I either want to know which corresponding value it has in column A, OR if he has MORE THAN ONE, I want to get 'wrong' as an answer.