Amith,
You can not have the same customer no. for 2 different customers.
For example, customer no. 50 for SP with account gr 0001
You can not create customer no. 50 for SH with acc gr 0002
You can create SP with customer no. 50, and have all other partners also as default 50. You can create this with one transaction of XD01 and account group 0001.
TW