Please follow the following steps in the Data Mapper to create multiple records on the Target end for single record.
Text schemas at both source and target ends have been used and their structure can be seen in the provided screen-shots.
Step 1 : Apply ForEach as shown below on root node.
Step 2 : Create a local variable as shown below on the root node.
Step 3 : Apply the below IFF Condition on Record node.
Step 4 : Use get-context on the element to fetch the value from local variable.
Step 5 : Use an IFF Condition as shown below on the element, it will parse the record only if the value coming in is X