Can someone be a "twice awarded Combat Infantry Badge recipient" from different wars (Korea & VN)?

Yes

Yes some even have a third award.

I saw several with a star when I was in. I went in right after Vietnam ended.

Absolutely. That is what the star on top of the CIB signifies. A CIB with two stars signifies WW II, Korea and Vietnam.

I served 21 years as an infantryman starting in the early 1960s met more than a few who had 2 Stars , meaning WW2 Korea and Vietnam.

Yes, actually it is the only way it must be 2 different wars

Yes some have 3 Korea,Vietnam and WW2

You just add a star... Is like combat jumps, a star for every combat jump...

30 combined years in all 3 components ( AD, NG, RES ) 1982-1992/1997-2017 not 11B for all of it.
Just Cause/Panama, Desert Storm, Enduring Freedom, Iraqi Freedom. If 11B and in the right duty position with the right unit one could've had 4 awards. Then you factor in Grenada, bosnia/Croatia? In the past 35 years there could be a good number of possible multi awardees.

There are more than five or six left! I served with two in Iraq in in 2005 they had served in desert storm and panama also which means there are more than what you think