1. Right-click the picture you want to make a copy of.
2. Click "Locate on disk".
3. A window will open with the picture file highlighted. Right-click the picture file.
4. Click on Copy.
5. Right-click any blank area in this window (do not right-click another file or folder).
6. Click Paste.
7. Close the window displaying the picture files to return to Picasa2.

Now you have a second file with the name "Copy of...".