Hi Ameen,
When you copy a company code to other co. code, the COA & Currency get copied depending on the choice of selection you make when prompted by the system, all the assignments that you can see in OBY6 will be copied, and the configuration changes to customizing tables done in the source company code get copied to the target company code. Based on the choice made for copying the COA, all your account determinations also get copied.
Hope this answers your question.
Regards
KIM Khan