Notifications: only first notification is shown

[rodvar]

We currently have testing code that pushes notifications every min to evaluate how the apps respond.
On android it works perfeclty on both apps, and tapping on a notification will open the app.
On iOS client, we have an issue. Only the first notification works as expected. The rest are being pushed to the OS but are not showing up regardless of the app being in the foreground or background.

Follow up of #89