Why a copy of my graphics file is created in the temporary directory

[ehud.behar at protonmail.com]

When I insert a graphics into my LyX document with the gui ("Insert>Include graphics"), even when the graphics file is in the same root directory as the lyx file, a copy of that file (with a different name, though; its new name is `0_Users_username_long_path_to_file_myfile`) is created in the temporary directory.

A look in the tex file that lyx creates in that temp dir also reveals the following few lines right at its beginning:

\batchmode
\makeatletter
\def\input at path{{/Users/udi/Downloads/}}
\makeatother

Why is it?

On the other hand, when I include the graphics with ERT code, a copy of the image file is not created in the temp dir, but the same tex code from above is still there.

It's not a bug; Everything works fine, I just try to understand the way that LyX works.