Viking, for years, was a brand built by Coachmen RV, a company located on the north side of Middlebury, Indiana. Clipper was a model line in the Viking brand.
Forest River Inc (which tends to look like a holding company owned by a holding company) has since bought Coachmen (and Dynamax, and Carriage, and a few others that were struggling financially during the last recession). Forest River RV, one of the manufacturing companies held by Forest River, makes many different brands of RV carrying the "by Forest River" logo
Immediately after the Coachmen purchase, F-R allowed Coachmen to continue operating independently, but as they did acquire the Coachmen brands, they started using some of those brands for products built by Forest River RV. In the past couple of years I've noticed more badge engineering, with some Coachmen branded products coming out of Forest River RV plants. If you are seeing Shasta, for example, that was a brand Coachmen acquired when they bought that company, and now it can be Shasta by Coachmen or Shasta by Forest River, however F-R Inc wants to do it.
If the travel trailers look almost identical, chances are they have been assembled in the same plant. I'm not going to venture a guess which plant for those specific models. There are several F-R plants in the Elkhart-Goshen-Warsaw area. I'm not even sure the Coachmen plants are still operating, as the last time I came through Middlebury (September) I came in from the east and went out through the south toward Goshen. I can say there is still a lot of Coachmen branded product coming out of that town. I didn't pay a lot of attention to what was sitting outside at the Middlebury Forest River RV plants I passed that day.
If F-R has plants in Oregon there is a chance that the Coachmen-branded trailers you are seeing in the Pacific NW are assembled there, rather than at the Coachmen plant in Middlebury, because transportation costs from Indiana are high relative to the prices of those trailer models, even moving 2-3 at a time on flatbeds. But no guarantees.
You'll see something similar among the Jayco lightweight trailers and foldables, and the Starcraft brand. Starcraft is a separately operated company wholly owned by the owners of Jayco, and Starcraft builds some product for the Jayco brand, and Jayco builds some models sold as Starcraft. But there is not complete product overlap, as you see among some Forest River brands, the Flagstaff/Rockwood twins being one example.