You don't want to arm them to play them back. If you are in Session View, you are playing Clips, the clips play one per track. If you have two guitar clips on the same track, you will need to move on clip to a new track and same Scene, then play the scene. If in Arrangement View, make sure it is not muted, not disengaged or output is going to master.
If these instructions confuse you, you should go look at Ableton basics. Ableton works very different in Session View than traditional DAWs. It is not hard, but does take some tutorials to understand.