Solution : https://service.sap.com/sap/support/notes/84936 (SAP Service marketplace login required)
Key words : 
additional key words vf01, 'change billing document' function, billing document statistics, additional accounting documents, duplicate accounting documents, billing document, function module, duplicate documents, accounting documents, financial accounting
Related Notes : 
       
| 352706 | Double accounting documents for billing documents | 
| 95614 | Correction program:missing FI documents f. invoices | 
| 95317 | Analysis: Billing docs available/accounting docs missing | 
| 86543 | Check program for duplicate FI documents | 
| 79234 | Incorrect statistics update in the billing document |