tcp_hdr_kind_and_field window COUNT vs. tcp_hdr_option_type window LENGTH

After a complete constructing the EBNF of nftables (needed by TextMate, 
LSP, and Vim syntax highlight), I notice many repeatedly overlaps of 
syntaxes within the parser_bison.y.

One example of such a overlap pair:


All within the tcp_hdr_option_kind_and_field, the Bison parse tree 
offers different pathways to the "same?" following `nft` expression:

     tcp option window LENGTH
and
     tcp option window COUNT


For 'tcp options window LENGTH', the Bison pathway is:

   tcp_hdr_option_kind_and_field->tcp_hdr_option_type->WINDOW->LENGTH


For 'tcp option window COUNT', the Bison pathway is:

   tcp_hdr_option_kind_and_field->WINDOW->tcpopt_field_window->COUNT


Is this intentional overlap? Or did I overlook some hidden feature(s) 
surrounding LENGTH and COUNT?



The Railroad diagram for latest 'tcp_hdr_expr' is only XHTML-viewable 
via a web browser 'file:///' from your hard drive (GitHub defangs 
[X]HTML; SVG is too big, PNG is too squishy):

  
https://github.com/egberts/vim-nftables/blob/master/doc/nftables-railroad-chart.xhtml