Should i get another air stone?

I have a 10 gallon tank for my two male Betta. Yes it has a divider so they both have 5 gallons. The divider is Plexiglas since apparently no one has a divider around me for less then 30 gallon tank. Anyways, I have an air stone on one side of the tank with one Betta. I was wondering if I should buy another one and put it with the other Betta.