Assign multiple internal customer number for single sales organisation .

Dear Experts,

My requirement is to assign multiple internal customer number for one sales organisation in inter company customizing.

For below customizing, customer code (ABC) already exists, assignment of another new customer (XYZ) is not allowed, since the Sales org. internal customer number assignment is unique.

Path is :

SPRO >SD >Billing >Intercompany billing >Define internal customer number by sales organization.

Kindly help me to know, how to maintain multiple internal customer for one sales organisation for inter company customizing.

Thanks in advance

Regards

rampe