Import only students.csv and enrolments.csv. In Data cleaning and analysis, expand Join and compare; choose students left, enrolments right, StudentID and Left join, then run. Expect five rows, S3 with blank right fields and E1–E4 each once. Download and reread the source-side fields. In a fresh page, replace the master with students-duplicate.csv for seven rows; restore the original master and reimport to recover five. Distinguish three students, two students with enrolments and four matched records.
