The difference is the coating method of the adhesive.
A single dot is made by solidifying a fine powder adhesive and transferring it to the base fabric (base fabric) in dots.
Since the adhesive is fine, it does not fading out even on thin materials, and it is difficult to get hits.
Double Dot has a two-layer structure in which a gel-like adhesive is used as the base, and powdered adhesive is piled up on top of it.
High adhesive strength can be obtained for a wide range of materials.