A named entity recognition system modeling this structure would encourage all the occurrences of the token sequence to the same entity type, thereby sharing evidence among them.
if the system has strong evidence about the label of a given token sequence, but is relatively unsure about the label to be assigned to another occurrence of a similar token sequence, the system can gain significantly by using the information about the label assigned to the former occurrence, to label the relatively ambiguous token sequence, leading to accuracy improvements.