Newbie, trying to solve weird boolean intersection issue

I know this is probably obvious to most. I think I found a similar topic here, however I didn’t really understand the answer. And I don’t know enough to be able to properly research the problem. Please excuse my lack of correct terminology also (italicized when I don’t know the correct term). Trying to teach myself.

I am simply trying to boolean two cylinders into a single object. The operation works, however, it leaves one of the cylinder’s outline curves as part of the solid where they intersect. The cylinders are both the same height and I can’t figure out why this is happening. I uploaded a before/after screenshot and the rhino file for reference.

LensBracket.3dm (3.0 MB)

The boolean doesn’t change the initial surfaces. Try: MergeAllFaces

Thanks for the reply. I tried your suggestion and it failed. The history says:
“Command: MergeAllFaces
Merged 0 polysurfaces. 2 polysurfaces could not be merged further.”

Actually, I tried again after Boolean and it seems to have worked. Thanks for the knowledge!

no worries, yeah it only works when they’re joined