At my historic database I get this issue when I try to manage modules:
Fatal error: Cannot redeclare class user_favorites_WT_Module in /home/h/o/ftp_host-sidendk/webtrees/modules_v3/widget_favorites/module.php on line 330
Also got it at the test database – but it suddenly worked. I have no idea how
That’s easy. The user_favorites module is redundant and in part copied by the widget_favorites version.
By visiting the admin page you triggered the system to delete the old one and so removed the duplication.
All as designed.