Do you mean "files" or "Table"? they aren't the same thing in current versions of FileMaker.
If you mean tables, you can create a script that imports all records from each table and then also update any auto-entered serial number fields so that the next new record in that table does not generate a record with a serial number value that duplicates the value in an existing record.
Please note that Report An Issue is intended for Reporting Possible Software bugs. Questions on how to work with FileMaker Pro should be posted in the FM Pro Forum Section. (See tab at top of this screen.)