In C:\Windows\Installer on my Win 8.1 64-bit system, I have 10 different files with the name format reflect_setup#.#.####-x64-10.msi, where # is a numerical value. The oldest one is reflect_setup6.1.909-x64-10.msi; there are five msi files for Reflect v6, and five of the v7 version of Reflect. There is no msi for the installed version I have, 7.2.4063,
This is not a reflection on Macrium, since this is presumably a built-in problem of Windows, one of long-standing (although some software is worse than others about leaving bits and pieces here and there; the most notorious one that comes to mind would be NVIDIA.)
I'm morally certain that there could not possibly be any use for the v6 installers, but, one never knows whether a feature that appeared in one particular iteration of the installer might, somehow, still make that file necessary. That's a little more than half a gigabyte of space being used, and I suspect that only the most recent one or two should be there. Those of us with SSDs are becoming more cognizant of whatever it is that makes the free space on our drives shrink so fast. Using Macrium, I am shocked every time I do a restoration at the difference in my C-drive size. Perhaps Macrium ought to advise us on what's safe to delete.