Second Material determines while doing DP90

Hi Experts,

while doing RRB via DP90/DP91, this is working fine but when we check details this shows original material and second material in dropdown list of original material.

we dont have any BOM or any type of connection with that material but only second material is assigned in ODP1.

i have tried to remove that material but this is giving another error of cost elements/taking another material.

please guide

thanks

Sunil