It looks like there are at least two villages called Chainpur, according to
this site, with one in
eastern Nepal and one in the
far west. According to
Khukuri House it is the
eastern Chainpur, along the Arun River, near Makalu, that is the source of the Chainpuri khukuris. This seems to conflict with Uncle Bill's sources, who, IIRC, said that Chainpur was in the Terai, the lowlands.
Chitlang appears to be either very close to Hetauda as Walosi's link seems to say or else pretty close to Kathmandu, to the Southwest, not far to the North of Marku, as shown on
this map according to information about halfway down
this page. These pages may refer to the same place, but it's hard to tell from the descriptions.
What strikes me as surprising is that at least the handles of the chainpuri and chitlangi styles seem to be pretty different from most other handles and pretty similar to each other. If the relevant Chainpur is the one on the Arun River, in Eastern Nepal and the relevant Chitlang is near Marku, it would be odd for the two styles to be so distinctively similar. OTOH, if the relevant Chainpur is
neither of the two, mentioned on the calle.com page, but is in the
Chitwan region, as
this site suggests, this similarity would be far less surprising.
Paul