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Kanchanaburi. These two achievements are both PvP achievements, there is no way you can do them in Single Player. Yes, it is possible to do on one console split screen, but you still need another controller for this, which for a flagging sake means another player. Also you are playing against another player not with him towards a common goal, making this a versus achievement, the fact that you can boost this with two controllers or with a friend does not factor in this.