I just noticed that I have one Saturation Knob.dll (v1.3.5) in C:\Program Files\Cakewalk\Shared Utilities\Internal and another in C:\Program Files\Cakewalk\Shared Utilities\Internal\Softube that is version 1.3.8.

Version 1.3.5 loads into Prochannel, but if I rename it then the other one (version 1.3.8) loads.

If I click the smiley logo on the knob, they are definitely different and the newer version seems more up-to-date.

So I will leave the older one renamed.

Anyone else see that?

Yes

I've tried renaming my 1.3.5 DLL and Tube Saturation no longer loads at all. Is there a step I am missing somewhere? 

Edit: I think I've sorted it, but twas a bit of a pain...

Not Tube Saturation - that's different. This is called 'Saturation Knob.dll'

Oops, yeah, I typed the wrong thing, but meant the same as you. Sorry.