The "men" can only be struck from face, not from back. However, only one of the two hands can be struck, it depends on which kind of posture("kamae") your opponent are using. A struck to the right side of body(one kind of "do") will often be ignored by referee because in the old days samurai will have a smaller sword in this position, which gives this position a good protection. Very important, because "tsuki" is somehow dangerous, junior practicer perform "tsuki" is forbidden both in match and daily training.