Mm, Illustrator is also rather peculiar when it comes to layers. When I imported my SVG to Illustrator, objects on each layer were grouped together, and then the layers were merged. That can be dealt with without too much trouble, but then when it comes to moving objects between layers... every obje...

Hmm, semi-multiple files. As in the file itself, and its backup which was designed earlier on - both then continued along different paths. I'm not completely sure but I may have opened one of them with Adobe Illustrator, saved it, and then returned to it in Inkscape... but it crashed before Illustra...