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

Yes

I've only met one with two stars, I think he said El Salvador Panama and Iraq he was to young for Vietnam

A friend of mine who died last year, Charlie Green, had three awards of the CiB. WWII, Korea, and Vietnam. Charlie served with the 27th Regiment (Wolf Hounds) of the 25th Infantry Division is all three conflicts. He was inducted into the Indiana Military Veterans' Hall of Fame in 2015.

During Vietnam it was very common to see two awards. One for Korea and One for Vietnam. Rare but saw a few from World War II Korea and Vietnam. Depending on the Date of the Conflicts will determine the number of individual awards. Don't know if any were awarded For Desert Storm or Grenada?
It would be extremely Rare to find a fourth award for World War I, World War II, Korea, and Vietnam. It would be Possible but extememely Rare.
If someone was 16 or 18 in 1917 lets say, then in 1941 they would be in around 45 Let us not forget their were two theaters in world war II so a third award could be granted for both the Euopean and Pacific Theater. Then Korean War which ended in 1953 The U.S had Military Advisors in Vietnam in 1950 but the war started in 1955 and esclated in 1960's. So Statistically it would be possible though by 1967 the WWI Vet would be 68 years of Age. If they were a Colonel or General it would be possible to obtain the 4th award. Possible but Higly not Probable.

The National Infantry Museum at Ft Benning lists 324 3 time recipients of the CIB.

when I got to 10th Mountain Division, I was friends was a MSG Infantry and in Panama, Somolia, and Afghanistan thus triple award.

Question: Was CIB awarded for combat troops in Grenada?

1st Qualifying Era
World War II: 7 December 1941 – 3 September 1945

2nd Qualifying Era
Korean War: 27 June 1950 – 27 July 1953

3rd Qualifying Era
Republic of Vietnam Conflict: 2 March 1961 - 10 March 1975;
Laos: 19 April 1961 - 6 October 1962;Dominican Republic: 28 April 1965 - 1 September 1966;
Korea on the DMZ: 4 January 1969 - 31 March 1994;
El Salvador: 1 January 1981 - 1 February 1992;
Grenada: 23 October - 21 November 1983;
Joint Security Area, Panmunjom, Korea: 23 November 1984;
Panama: 20 December 1989 - 31 January 1990;
Southwest Asia Conflict: 17 January - 11 April 1991;
Somalia: 5 June 1992 - 31 March 1994;

4th Qualifying Era
Afghanistan (Operation Enduring Freedom/Operation Freedom's Sentinel): 5 December 2001 - TBD;
Iraq (Operation Iraqi Freedom/Operation New Dawn): 19 March 2003 - 31 December 2011;
Iraq/Syria (Operation Inherent Resolve): 15 June 2014 - TBD

Why do people pretend to be combat veterans when they are not? I don't understand why, what is the point? I am,.. and to tell you the truth I can't distance myself enough from that time of my life. I don't regret my service,.. idk,.. I just don't think there was anything that glorious about taking another life, or holding my friend while he was dying. Why are people so fascinated with this? There is nothing good in, or about war.

I had a neighbor who was awarded the CIB for WW 2 and Korea, branched medial after Korea and was awarded the CMB for Vietnam!