Using the instructions above, I was able to merge (move) a name mapping file from an existing to a new project. According to the instructions, you can also merge two existing name mapping files, though I have not had a need to do this.
I agree with @dmiscannon.
Since I see that you just want to use the namemapping from Proj1 to Proj2, you can simply do that by copying the NameMapping file from the Proj1 folder to Proj2.
i.e. Copy C:\TC11Projects\Proj1\....\NameMapping\NameMapping.tcnm
Yes you can copy files or merge files.
But essentialy it would be two files
if you are using same application but testing two funtionalities in your two projects you will have two distinct namemappings for two projects and maintaining would be double the work.
so I suggect that first merge two files and share the mapping among two projects.
You can share mapping by right click (new) project, add existing items, and point to merged file.