Weird double reflection in mirrors

Hello everyone!
I’m trying to create a fake mirror, so I made a metallic material (Metallic 1, Roughness 0) and placed a Sphere Reflection Actor in front of it. I would like to just reflect the Sphere reflection, but instead of that it captures as well the SSR so it appears a double reflection in the mirror that looks just terrible (the cool one and a way more glossy one).

How can I reflect just what the Sphere Reflection affects?

Thank you in advance!