DBBRCR=Double Broken Circles -- see Herz Nevada Checks book, page 22, chip mold #68.
I've always assumed it is a variation of the "H" mold (#16 in Herz book) by H.C. Edwards, though don't know if that has ever been proven.

BTW, I have a white $1 Americana Aruba in the same style as the ones you show.