Can you rent multiple devices at the same time?

Absolutely. It's also much more fun when there are different devices. And you shouldn't forget, when one device is being played, what does the other person do? And depending on the numbers. If I have a party with 80 people and I only have one device, yes, that's also fine of course. But if I have multiple devices, more people can play, people can take turns and so on. The number of devices is usually correlated with the number of guests.