CalebIddings

public XSSFSheet cloneSheet(int sheetIndex, String requestedName) {
    validateSheetIndex(sheetIndex);

    XSSFSheet sourceSheet = getSourceSheet(sheetIndex);
    String targetName = resolveSheetName(sourceSheet, requestedName);

    XSSFSheet clonedSheet = createSheet(targetName);

    copySheetRelations(sourceSheet, clonedSheet);
    copyExternalRelationships(sourceSheet, clonedSheet);

CalebIddings

public XSSFSheet cloneSheet(int sheetNum, String newName) {
    validateSheetIndex(sheetNum);
    XSSFSheet srcSheet = sheets.get(sheetNum);
    
    // 1. Name Resolution
    String validatedName = resolveNewSheetName(srcSheet, newName);
    XSSFSheet clonedSheet = createSheet(validatedName);

    // 2. Relationship Cloning
    copySheetRelationships(srcSheet, clonedSheet);