Only show Data return if there is more than one occurance of the output

Hello,

I've trawled the Forum and can't find the answer to this, but it's difficult wording....

I'm building a simple table report in SQL 2.0, I have set all fields and date parameters etc, however I only want the output table to show the results if one of the fields has a duplicate.

For example: The report brings back maybe 500+ rows in a certain date period, a field in those rows would be "Customer ID", I want the output report to only show rows where within the "Customer ID" field there are 2 or more occurrences of the same ID - In essence a report to only show repeat customers.

Is this a possibility, any suggestion would much greatly appreciated!

Thanks