How to dynamically determine and categorize duplicate value in Tableau

Question

Sample Dataset:

ID | Date | DollarAmount
 1 | Jan  |    50
 1 | Jan  |    20
 2 | Jan  |    10
 1 | Feb  |    20
 2 | Feb  |    10

Goal: Dynamically determine if a particular period in time has a duplicate value based on the ID column.

Sample Graph to be created:

What I already tried: I tried adding filter based on Number of Records but it filtered based on the TOTAL observations across the data-set, not date ranges.

Answer 1

Apparently you define a duplicate records as those that have the same value for the ID and Date fields, where Date is really a string containing the abbreviation for the month name.

In that case, define a (Boolean valued) LOD calculated field called [Duplicates] as {FIXED [ID], [Date] : Count(1) > 1}

Add [Duplicates] on the color shelf, Sum([Dollar Amount]) on rows and [Date] on the Columns.

You will find the True and False values on the Color Legend. If you want you can edit the aliases for those more clear label such as Duplicates and Non-Duplicates

If you have a true date valued field instead of a string, you can even use DateTrunc() function to define the duplicate test at the granular level.