Duplicate settings in Pref File

I can confirm that these errors appear only after a toolchange has been done after LinuxCNC started.

I Have runs som programs but error was stil happening. I have no Tool Change don but i have changed the Ofset tabel in G55 and G54.

than i get a duplicatet items in the file

I'm having the same problem as well. The system _name values get entered twice. The file change happens on exit, if I've edited my offests or done a tool change.
Using gmoccapy, dark theme. I have a glade vcp panel that handles air/mist/dust collection

I can reproduce it by running Gmoccapy from LinuxCNC 2.10 with a pref file which is created by 2.9 or earlier, so it has lowercase names for "system_name_gxx" and so on. After that, entries like "system_name_G5x = G5x" are added additionally to the existent "system_name_g5x = G5x".
If you try to run that with 2.9, it gives the duplicate settings error.
Now come the weird thing: Gmoccapy from LinuxCNC 2.10 works with the duplicate settings because it only takes those ones with the capital letter.

Internally Gmoccapy works with the capital letter, so "system_name_G5x", "Gtk_theme" and so on.
In 2.9 the configparser does convert the settings name to lowercase and the same configparser on the same pc but in a 2.10 environment does not sonvert it and write the capital letter. I have really no idea why the configparser does now take capitals into account.

However I provided a fix here: github.com/LinuxCNC/linuxcnc/pull/3181