If I shine an electron beam in a sample and it returns, for an example, an X-ray wavelength compatible with both $K\_\alpha$ of copper and $L\_\alpha$ of hafnium. How can I tell the difference between these elements?

Edit: Using Moseley Law [here](https://imgur.com/a/yhGzAxj) I get copper for $K\_\alpha$ and hafnium for $L\_\alpha$ for an wavelength of 0.155 nm.