A bit of outdated forum request.
The tabular model generates a json file, default name is model.bim.
It is possible to open the file in for example notepad++. Somewhere after the remark "tables": you can copy the part for the dimension you would like to copy. When copying note to make sure to modify the "name":
Also make sure to make a copy of the .bim file before trying this.

Like this it is not all that hard to do.