Do you think I must change an extension of such file? Or to add a some suffix to the file name?
Maybe suffix the filename with …_CS (Commercial Skin). So Metro DW would become Metro DW_CS. And since DW doesn't say much. Metro_CS would do it nicely.
If you download the skins using the link in the Skins map, you get all the old skins. The askins.zip file apparently is not updated with the new skins.