only connect player timer to _on_hit_end once

scenes/ball/ball.gd

@@ -27,6 +27,7 @@ func _on_hit(hitbox: Area2D) -> void:
 			var player: Player = hitbox.get_parent()
 			var timer: Timer = player.hit_timer
 			launch()
+			if not timer.is_connected("timeout", _on_hit_end):
 				timer.connect("timeout", _on_hit_end)
 			EventBus.ball_hit.emit(player.id, linear_velocity)
 			is_hit = true