I don't see how that could happen.  If you have two printers, they have to have different printer names (the Windows name of the two printers must be unique).  For example, if you have two Canon Pro-100 printers, you might see:

Canon PRO-100 series
Canon PRO-100 series (Copy 1)

These two printers will be treated as completely different printers (which they are) by Qimage.  So if, for example, the (Copy 1) printer is the one with PC ink, each time you switch to that printer, Qimage will restore the settings for the media type you are using and it'll restore all your settings for PC inks.  Conversely, when you select the one without the (Copy 1), it'll restore settings for the OEM inks.  I would think that would be extremely helpful in your situation!  As long as the two show as different printers, Qimage will never mix up the settings you used for one with the other.

Regards,
Mike

Not really possible as in reality they are two different drivers and you can't copy settings from one driver to another even if technically they are the same driver type.  What I would do is use printer setups: that's why Qimage is so flexible in that area.  For example, create and save two printer setups like this.  Name the two setups:

Canon Pro-100 Good Matte Paper 13x19 (Canon ink)
Canon Pro-100 Good Matte Paper 13x19 (PC ink)

Then when you are doing your proofing, you recall the "Canon Pro-100 Good Matte Paper 13x19 (PC ink)" printer setup and set things up how you like.  When done, you simply recall the other printer setup named "Canon Pro-100 Good Matte Paper 13x19 (Canon ink)" and print your final.  When you load that Canon ink printer setup, the printer is changed to your printer that prints Canon inks, the paper size is set to 13x19, the media type is correct, profile is correct, etc.

So in summary, instead of changing the printer, you just click the "Recall saved printer settings" button next to the "Properties" button that opens the driver and select the printer setup you want.

Regards,
Mike