Interesting point.
If I understand you correctly the defining thing is that the auger either turns or could turn at a different RPM from the impeller. I suppose you could also argue that the impeller has to be in a separate, albeit connected housing as well. Point taken.
To post a link that you just "click" on you highlight the word or phrase that you want to represent the link, such as
this, and then click on the button above the typing area that looks like a blue sphere with two links of a chain ( 5th button from right). A box will appear that allows you to insert the actual URL. You can even put in other URL types or protocols if you want such as e-mail, ftp, https even news. I've only used the URL, http option. If you change your mind you can remove the link by highlighting the word/phrase and clicking on the button to the right of the one you used previously. It has a broken chain at the bottom.
Yes, it seems that the commonly accepted definition of a 2-stage is the presence of an impeller that is physically distinct from the auger.
As for posting links I can't for the life of me figure what I'm doing wrong, I've been posting links in all forms and fashions on forums for almost 20 years but this is one of the very few where it just won't work. This forum doesn't seem to allow manual formatting with BBCode tags such as [url][/url] and when I use the box I have no problem pasting the url into it but it invariably yields a blank after I hit the OK button. I find this puzzling because the image box works flawlessly...
Honda HS928 TCD - If you lived where I live you'd have one too