I just committed a fix for this issue.
New project-layouts now get mixed with existing layouts (tabs of first tabcontrol go into first existing tabcontrol, 2 => 2, etc.)
Only if the new opened layout has more tab-controls, than the already opened layout, C::B creates new controls.
We still can get problems, if we have multiple projects with the same title and filenames, but in different locations.
I only use the projects title and the relative filename as id for a tab. If I use fullpaths, the layout-file would be broken if someone moves the whole project to a different location.