Hey there. Sorry about this. As you can see I made an import here. As a precursory step to the import a custom merging script is run to avoid duplication of content. The OSM_layer tag indicates that a matching stream was found in OSM, that was tagged with layer=-1, whereas there was no such tag in the imported data.

In this case the imported data is correct, but I forgot to remove the tag. I've done so now. Thanks for pointing this out.