I have a bunch of layers that are named layername_number+number that I want to merge. I need their names as source attribute so I used the "merge shapes layers" algorithm found under SAGA in the processing toolbox. While that does add the source layer name to the attributes of the merged layer (as "LAYER"), it removes the underscore and plus. Is there any way to prevent this?
The layers have no unique naming pattern (you could have name_0+100 or name_010+0, both resulting in name0100) so I can't reinsert the underscores and pluses afterwards either.