Number of components in subBOM not adapted to the number of subBOMs

When I upload/import a BOM that contains sub-BOMs, the quantity of the subBOM in the general BOM list is changed to the number of the currently loaded BOM list, but not the contained articles/components of the subBOM.
When calculating the cost price, for example, 2 products of the SUB BOM are displayed but only the price of one product.
In addition, my original BOM list for the sub-product is overwritten.