To Save a Copy of a Block with a New Name (Block Editor)

1. Click Tools  Block Editor 
2. In the Edit Block Definition dialog box, Select the block. Click Edit Block

   The Block Editor opens up. Edit the drawing.

3. Click Block Editor tabSave Block As.
4. In the Save Block As dialog box, enter a name for the new block definition. Click OK.
5. To save the block definition in the drawing, click File menu Save.