Widget mess after theme preview

If I preview on the themes I have all my widgets are messed up.

– Some of the the widgets I have on my default website are removed (in best case they are put in the Inactive section).

– Widget are placed in different places (ex: blog sidebar is placed in the menu section)

– Deleted widgets (like meta) reappears.

All this happens just on theme preview.

Is this normal?

Using:
Wordpress 3.9
Themes: Genesis child themes