You could check it manually. In the code run when the two areas collide, verify if it is the sibling Node.
Edit, if you have a script in Hurt_Box :
onready var own_punch = $"../Punch Hit" #".." represents the parent Node.
. if area != own_punch: #don't punch yourself
. . pass #all good, you can punch
Alternatively, if enemies can only hurt players, and vice versa, you can use collision masks. punch_player collides with hurt_enemy, and punch_enemy collides with hurt_player.