Me thinks this is more on the iPad side than in Moodle ... accessed with a browser or from the Moodle App.
But ... here's some info to read:
clip from resource above:
A big step, not yet taken
Should Apple move forward with
Shared iPad as a cornerstone feature of iOS, it will likely do so with
iOS 10. Introducing the feature specifically for education at this stage
represents a good testing ground for Apple and a way to reassure
education customers that the company understands their needs.
One of the items ... multiple user iPads.
So it might be a combo of iPad version, feature turned on, the Moodle Mobile App, AND the admin side of the Moodle.
Years ago, there was a product for PC ... Windows only ... a 'buddy card' I think that's what they called it. One physical pc but 2 users with their own keyboard/monitor/mouse. Problem ... they shared the same browser ... cookies, history, etc.. So Student User A logged onto Moodle. Student User B (on the buddy) logged onto Moodle to find they were logged on as Student User A.
Chrome and FireFox ... don't think you can get either on an IPad ... when you create Multiple users in Google for example, both of those browsers will launch with a 'multiple user screen' asking who do you want to be.
Does Safari behave that way?
So ... they might have to upgrade their iPad OS when Apple finally provides multiple users on a shared iPad feature.
OR, in the interum, could possibly use Safari.
How is the Moodle setup for authentication? Another area to explore!
Is the first iPad user actually logging out?
Sorry ... 2 cent response really. :\
'spirit of sharing', Ken