Both original and mirrored image got imported into an assembly

Hello, I made a left version of an object and using mirror, I made the right version. As far as I recall, in the past, somebody in the forum suggested me to make either the original or the mirrored assembly invisible before 3D printing. Now, I imported this file into another assembly and found that both left and right versions of the object show up in the assembly. What suggestion do you have? I only want to import the mirrored part.

SolidworksAssemblies