To play a powerful guitar chord one can choose to include as many notes as possible… or double the ones that are played. An example of the former would be (in tablature):
C: 3-3-2-0-1-0 (an unorthodox thumb may be used for the low G
An example of the later:
C: x-3-5-0-5-0 (x means muted)
Notice the “same” G and E is played twice!
(It’s never the same, you know. There’s a nice article about a letter from Richard Feynman partly about this fact. So Feynman knew string theory ha ha.)