In Tableau, I want to create a box and whisker plot. So for that, I Drag out and drop the fields but it seems like firstly it removes the duplicates and then did its calculations. for example, two rows in my data set have the same value so it removes one and by using the second it did its calculations. This results in dissimilar means from the actual means.

I am not able to find out the problem that why it is not considering all of the data. Tableau should notify me before removing the duplicates. Can anyone help in this regards?