I don’t want to sound harsh, but in my opinion, this topic is perfect example of 2 pages wasted on attempts to solve a self inflicted problem.
OP is full of excuses for the wrong workflow that he, himself accepted.
Sometimes I do this, sometimes I do that… and it doesn’t work.
I know that is not good, but I still do it.
Well, don’t.
If something doesn’t work well, don’t do it that way!
Instead of complaining about features that do not support accepted workflow, why don’t you develop another workflow that does support existing camera features?
Mark one of your 20Ds A, the other one B.
Format all your CF cards in computer, take a sharpie and mark half of them A, and the other half B.
Cards marked A use only in camera A, cards marked B, use only in camera B.
Do not mix them.
If you feel short of memory cards, buy some more, they are dirt cheap these days.
In your download folder, create one top level folder and mark it A.
Create another one called B.
Images from cards A download only into the folder A, images from B cards, download only to folder B.
Post process only images from either A or B folder at the time.
When you’re done, name finished pictures any way you like and save them in appropriate folder.
Voila, problem solved!
