Check if there is at least one not-unquie value in column (without using a helper column)

  |        A      |          B         |     
--|---------------|--------------------|----
1 |   Product     |    Check Unique    |   
--|---------------|--------------------|----
2 |   Product_A   |         yes        |  
3 |   Product_B   |                    | 
4 |   Product_B   |                    | 
5 |   Product_C   |                    | 
6 |   Product_D   |                    | 
7 |               |                    | 

In Cell B2 I want to have a formula that is doing the following:

= If there is at least one value in Column A that is not unique then "yes" else "no"

I know I could achieve this with a Helper Column using COUNTIF but I would prefer a solution without a Helper Column.

Do you have any idea if this is possible?

>Solution :

Use COUNTIF:

=IF(OR(COUNTIF(A2:A6,A2:A6)>1),"Yes","No")

in pre-O365 formula should be entered as array formula