1. A method executed by a computer, comprising: receiving first clusters generated by a first clustering process, each first cluster including one or more records; applying a second clustering process to the received clusters to generate second clusters, where the second clustering process differs from the first clustering process; comparing the first clusters generated by the first clustering process to the second clusters generated by the second clustering process, the comparing including: determining a duplication metric, the duplication metric measuring mergers of records that belong to separate first clusters into a second cluster; and determining an overclustering metric, the overclustering metric measuring splits of a first cluster into two or more of the second clusters; and displaying results of the comparison for evaluating and modifying the first clustering process.