I missed that you already pointed out that you thought they were Czech. Because of the others you were showing I thought people might mistake then for Czech.

About the center strand. Are they indeed molded? Is there a seam? I think they may be lampworked and then rolled into a one part mold to get the grooves and final shape. I have seen Czech lampworkers do this quite often. (Same with Indian and probably Venetian as well). It does not look like a shape that I think is molded with tongs in a two part mold. It is also a shape that could be made freehand, but they very consistent, so it would surprise me.