Variable product copy EAN from product attributel

Dear,

When uploading EAN’s via “Copy from product attribute” for variable products it results each variable product get the total amount of EAN’s. Eg the product is a shirt in size X. It is sold in size X, Y, Z. All variable produchts get the EAN’s for product X,Y,Z. instead of only X, Y or Z. Can you please give advice / direction to solve this issue.

Thanks,

Edwin