Solution : https://service.sap.com/sap/support/notes/97773 (SAP Service marketplace login required)
Key words : 
additional key words double document numbers, attached analysis program zacorr66, choose 'interval -> change status', current current number level, asset line items belonging, internal document number assignment, highest assigned number displayed, internal 'document numbers', current number level, column 'maximum numbers
Related Notes : 
       
| 97844 | AB08 reverses more than only one document | 
| 50683 | Entity copier: Number range transport |