Given the fact that the style of the dishes are the same (ribbed) and he decoration is the same (same flower cluster, blue band) it is probably safe to assume that they are from the same maker. Whether that maker is the one on the marked piece or not is the question.
Some thoughts this discussion raised to me:
If they are fakes would it be more advantageous to fake a Triumph Limoges, and therefore mark it as such, or to leave it blank and pass it off as something else?
Maybe they just missed marking the piece? Sometimes a sugar bowl is marked, but not the lid. Does that mean the lid is fake? Maybe there is a piece of a 2-part item that is missing, like an underplate? Perhaps that piece is marked, but you don't have it.
Just kind of throwing that out there.