Costing materials, CK11n overheads in costing structure

Dear CO experts,

I'm having an issue with CK11N,

I'm trying to calculate a cost for a composed material ( which has 2 sub meterials ; material.01 and material.02)

in the costing structure, the overheads of the 2 submaterials is of the same value and it's not correct it's actually the sum of the material.01overhead + material.02 overhead.

Can someone plz explain to me why the value of overheads is showing this value instead of the value of each material separtely?

Best reagrds,