cygterm.exe starts instead of ttermpro.exe by Alt+D(Duplicate session) key - Tera Term Ticket #34955 on OSDN

Problem:
cygterm.exe starts instead of ttermpro.exe by Alt+D(Duplicate session) key.

1) start ttermpro.exe
2) [New connection]
   - Host hostname:22  <<= Port is designated after the host name.
   - Service SSH
3) click a [OK] button.
   ===> Connection success
4) Alt+D or [File]->[Duplicate session]
   ===> cygterm.exe starts each time instead of ttermpro.exe.
        I'm thinking the behavior ttermpro.exe starts is right.

I connect to VM of a local machine using NAT.
I'm happy if this behavior is improved.

Addition:
When connecting to telnet port(23), Alt+D is expected behavior.
  eg.)
   [New connection]
   - Host hostname:23  <<=
   - Service SSH