Do I need two gliders/bouncers for twins?

I bought this same exact model except in a different color at a mom to mom sale for $50. It was originally $180 at the time. Now I think it's sold at Buy Buy Baby for $170. The swing seat comes out and acts as a bouncer. Anyway, we found out we're having two girls, and I found this pink version on Amazon for $150 AND it's eligible for Amazon's baby registry completion discount. It'd cost me like $130 after tax. The trouble is the discount is only good for a one time use, so I have to make up my mind as to whether it's necessary for me to buy a second glider/bouncer.