In the case of hazards aka TSpikes, Spikes and Stealth Rock, the Plus version counts as a separate instance, meaning normally when you use one of them, using the move again repositions the first hazard, but when using it as a Plus Move you can have 2 places affected by each hazard
Additionaly, just fyi, for some reason Meowstic-Male gets access to all 3 in this game, have fun