道道 is the reduplicated form of the classifier 道, which is used for long, thin things (e.g., rays, lines, streaks) and for courses of a meal. Reduplication turns it into a distributive meaning – 'every line' or 'each course'. This form is uncommon in everyday speech and is mostly seen in literary or formal contexts (e.g., military terminology: 道道防线 'every line of defense'). The source data provides no English gloss.