There was a time when Moss US owned Moss UK, and you could only get
TriumphTune (part of Moss UK) through Moss US. (Most people figured
out that ordering direct was a better deal, although returns are a hassle).
Both family-of-Moss catalogs (for Triumphs, at least) seem to share
the same drawings, though Moss UK uses factory original part numbers
(as does TRF) instead of their own system (as does Moss US).
Moss US divested of Moss UK about four years ago. A conglomerate
called M&G now owns the former Moss UK outlets, and more.