Manufacuter code get changed in MIGO

Dear All,

We are using MPN material functionlity(HERS mat type). In which we are facing error in MIGO, that manufacturer code get changed in MIGO.

Scenerio is I have created mpn code 'A' and assigned manufacturer no '1'. Further i have created PO using this MPN code. Now i came to know that the manufacturer code which i have used is wrong and I replaced the manufacturer no'2' in the mpn code.

At the time of MIGO, I have noticed that system is showing manufacturer no '2' in the screen. But I have created PO using manufacturer no '1', and manufacturer no '2' should not be captured in the MIGO. Since it is old PO and already released. Why system is behaving like this.

Regards

Amit