Organize duplicates in Excel without deleting

I'm attaching a workbook that I think does something similar to what you are asking.

The formula is a bunch of things nested, but basically breaks down like this:

If there is only 1 of something in the column stay blank (its not a duplicate)

If there is more than 1 of something, check if there has been another example of this in the column above.. (is this the first time we have seen this?)

If this is the first example, give it a number (+1 whatever the largest number is so far)

If this is the not the first example, check above for its number and assign)

This way, you should be able to filter your table by a number and get a 'group' of duplicates.

You will have to change the formula around a bit so the column/cell references match your data, hopefully it makes sense.