A system according to certain aspects improves the process of creating secondary copies of data (e.g., creating backup copies). The system can compute the score of the data (e.g., a computer file storing information) to be backed up, and determine whether the score satisfies one or more threshold criteria before backing up the data. In one example, a change in score indicates a change in the content of the data. The threshold criteria may be that the score be different from the score of the most recently backed up copy of the data.