Currently, workbook duplication doesn't automatically preserve "Send to table" relationships. When you duplicate a workbook, the feature to maintain these connections across tables isn't available yet. [1]
However, we're actively working on this functionality - future releases will include the ability to duplicate workbooks while preserving relationships between tables.
For now, you'd need to manually recreate your "Send to table" connections in the duplicated workbook by setting up the exports again between your tables. [2]
If you need any more help with duplicating workbooks or managing "Send to table" columns, please let me know. Would you like to share more about what you're trying to achieve so I can assist further?