Most played cards in Machine Head:

1 Decks
Duress
4 copies - 4 average
Hymn to Tourach
4 copies - 4 average
Wasteland
4 copies - 4 average
Badlands
4 copies - 4 average
Bloodstained Mire
4 copies - 4 average
Red Elemental Blast
4 copies - 4 average
Dark Ritual
4 copies - 4 average
Withered Wretch
4 copies - 4 average
Phyrexian Negator
4 copies - 4 average
Hypnotic Specter
3 copies - 3 average
Gorilla Shaman
3 copies - 3 average
Blood Moon
3 copies - 3 average
Pyrostatic Pillar
3 copies - 3 average
Planar Void
3 copies - 3 average
Null Rod
2 copies - 2 average
Diabolic Edict
2 copies - 2 average
Powder Keg
2 copies - 2 average
Rack and Ruin
2 copies - 2 average
Strip Mine
1 copies - 1 average
Necropotence
1 copies - 1 average