OK, in other posts I had advocated coming into a nation/territory from different/multiple directions to get multiple units on the Tactical battlefield. Last night I realized that is NOT what is happening. What you can do is to have units of 2 or 3 different Tech levels and that is what gives you extra icons/units. Try hitting a country with Level I,II,& III Fighters and Level I,II,& III Bombers and you will be unstopable. This confusion on my part again speaks to why it would be nice to hve different icons for the different Tech levels. Also other than this don't see much difference between the Tech level units on the Tactical Battlefied.
Ummm yeah, I figured that out tonight. I started the game with medium technology on a medium map. That was even more fun, especially with my nice new tank pictures. It was nice having multiple stacks of units to attack with.