I tried this on 2 devices, an ipad and a Samsung Galaxy. I was able to access the events at the same time and check people in. I am not sure if there will be any unforeseen hiccups in doing this though (there's always a catch, right? ). Were you able to attempt the 10 ipads with the same login?
Sorry should've updated this. Below is the response to the Marketo Case I opened.
"Hi Ryan , thank you for contacting Marketo support. My name is Devin and I'll be happy to help you. You should be able to log into all of them with the same credential."
Can confirm that we used the same credentials across 5 devices without issue.