The GN had a LOT of locos with the Belpaire fireboxes. Most of the GN classes built after 1890 had them.
The GN and PRR were the only major roads to use it widely. Interestingly, in spite of having no known corporate connections, the two roads also shared electrical standards for their electrifications, and motors from each were run at various times on the other. Do to differing traffic patterns and track profiles, none of the exchanges were particularly successful.
Maybe they had a similar steam exchange program?