Describe the bug
When duplicating a page in the Panel, it also duplicates the .lock file.

To Reproduce
Steps to reproduce the behavior:

1. Go to a page in the Panel (it should have images to offer the "copy files" option)
2. Make some changes to content fields, but do not save the page
3. Settings > Duplicate
4. Leave slug with -copy as is
5. Enable "Copy files"
6. Click "Duplicate"

Expected behavior
The resulting content folder should be free of any .lock file.

Instead, the .lock files gets copied and the id in the file is of the original page, not the renamed one. (In other words, there's not -copy in the file.)

Kirby Version
3.3.3 and 3.3.5-rc.1

Desktop (please complete the following information):

• OS: macOS
• Browser: Safari
• Version: 13.0.5

Additional context
Not sure if it's relevant, but this is on a multi-language setup.