Identify and separate duplicate coordinates

[DENSAN]

Hello,
I have a text file with coordinate points (XYZ in CSV format) and for the final result I need to have the following:

• Identify records with duplicate XY values
• Create a new list with unique values XY (Z value included)
• Export a separate list of all duplicate XY values
  (Z value included)

I am new to access but getting familiar with queries and tables. I would like some suggestions on the correct approach and what tools to use in this learning process.
As a starting point I was thinking about creating a math query to create an identifier (i.e. X Value - Y Value = Duplicate tag) then query using duplicate tag.
My attachment is just a small part of the entire dataset and the order of the records is not important.
Thanks,

[June7]

An aggregate query can identify duplicates:

SELECT SampleData.X, SampleData.Y, Count(SampleData.Z) AS CountOfZ
FROM SampleData
GROUP BY SampleData.X, SampleData.Y
HAVING (((Count(SampleData.Z))>1));

An aggregate query can return unique XYZ:

SELECT SampleData.X, SampleData.Y, SampleData.Z
FROM SampleData
GROUP BY SampleData.X, SampleData.Y, SampleData.Z;

Or:

SELECT DISTINCT x, y, z FROM SampleData;