Hello!
I'm not sure if I'm setting the dupeboxes correctly but when all blueprints have been constructed and belts have been linked, the train stop says:
"Subboxes 5: -activated 0/5 -can be activated 5/5 prodbox: inactive"
When I click activate, I get this error:

The mod dupebox (0.6.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event dupebox::on_gui_click (ID 1)
'entity': table expected, got nil
stack traceback:
[C]: in function 'associate_character'
dupebox/control/prodbox.lua:267: in function 'teleport_player_inside'
dupebox/control/prodbox.lua:112: in function 'process_dupebox_activation'
dupebox/control/dupebox.lua:262: in function 'activate'
dupebox/control/events.lua:141: in function <dupebox/control/events.lua:135>
(...tail calls...)