Many of these are in fact the same fish- "Dollies" tagged in the Fraser River drainage have been found in the Skagit. Wouldn't be at all surprised if they moved into the Squamish as well. I've hooked many Sauk/Skagit Dollies that look like your Cheakamus fish (tall and thick, broad backs). It just depends on timing. These fish move around a lot. This is also what happens when you require C&R- the bigger fish tend to stay alive longer. Nice job on the Steelie!