inventory double gain?

inventory double gain?
Hi,At the beginning of a new project,we purchase some materials for testing.Since there are not corresponding material codes,we consider the cost of these materials as expense and this expense would go to the relevant project since we set WBS in the PO.Later,when we apply the material codes for these materials,we need to adjust the residual test material to their material codes.In this case,the inventory gains would create.For consistency,we hope this gain would also go to the same project.But the currently situation is the inventory gains is created from cost center.And then they are taken to stock and consumed to projects in the production.That means these materials cost will be double in the project profitability report.Would it be possible the inventory gains is created to WBS (Project) How?Like MB1C and movement type:to post those stock gain,give an option to fill the WBS?Your consideration wil be high appreciated.Thanks