There has been some discussion on the need to restrict multiple people from using the same login to access moodle via mobile app. Unfortunately no solution seems to be forthcoming, yet.
It's a shame because the uniquelogin was integrated into the Moodle core because it is a real and clear requirement. Developers of the mobile app must try to recognize this user requirement and given the common database, try to figure out a way that Uniquelogin is enforced for mobile access also. The imperatives of mobile access is inescapable today, and mobile dev cannot wash their hands off this issue but saying that there is no solution. Else the browser solution restriction is also negated by this backdoor.
I request the dev team to revisit this issue and provide a solution to the community.