Looks glued to me too, if you look between the two sides there is a brownish line in between which is usually a glue line.
According to Bart some old hones that are glued to BBW are not suitable to hone on the BBW side because that BBW layer came from a far away piece of the mined rock whereas the natural combos share sharpening properties from being close together in the vein. I haven't tested this but it was interesting to hear.