When a cloned app is running in the background and you don't use it for a while, your device may reclaim it to save battery and improve the performance of other apps. There are a few ways you can try to avoid this if it's impacting your ability to access and your cloned apps:

Turn off 'Power Saving Mode'

The name of this setting varies between devices, but can usually be found under Settings > Battery and disabling the 'Power Saving Mode' that's on by default. This will prevent your device from reclaiming Multiple Apps.

Allow background activity

Navigate to Settings > Apps > Multiple Apps > Battery and look for a setting to 'Allow background activity' which will let Multiple Apps and your cloned apps continue to run in the background.

Add to 'Apps that won't be put to Sleep'

The name of this setting also varies between devices, but can typically be found under Settings > Battery or by searching for "Background usage limits". Make sure and your desired cloned apps are listed under 'Never sleep'.