When duplicating anything in the content browser, UE4 automatically creates a copy in the same folder, but with a slightly different name. This works most of the time, but for what I’m doing, it will not work. 
I need to be able to duplicate a material instance, and then simultaneously replace another in the same directory.
Example: I have 2 material instances. Both share the same parent material. If I change one material instance, I would like to propagate those changes to a duplicate material instance. The other material instance already exists, and is already applied to dozens of static meshes. So, I have 2 options. I can either, duplicate and update the several dozen static meshes with the NEW material instance, or I can duplicate and replace an existing material instance, which would therefore save gobs of time.
I recommend a “duplicate and replace” function so that I may save gobs of time. 
Example: Right click on material instance > “Duplicate & Replace”. Tadah.
If there is another way to do this, can a reply be posted to this with the answer?