Unfortunately,the transformations don't include a straightforward way to duplicate rows in a dataset based on a specific condition. You would usually handle such a transformation in the source query (if dealing with a database) or use a compute service like Azure HDInsight or Azure Synapse.
If you're working with a SQL-based source, you could write a query that performs this transformation at the query level. This could involve using a Common Table Expression (CTE) or a combination of UNION ALL statements.