related to duplication of code

i am using sap b1 with 36 patch.

i want to generate new house bank in house bank account -setup but when generate house bank following error is shown " to generate this document first define the numbering seris in the administration module "

in this house bank account -setup 4 banks but out of four bank two bank having same bank code.

this error is coming becouse of two banks with same bank code .so how to resolve this problem please send solution.

regards,

sandeep