I do not know about Robot framework but i handles two devices same time in one suite. All things i have done in Java.
So high level approach would be Create Master script-- Which handles interaction between two devices.
Like
Master.java
{
Device device1 = new Device("Device1");
Device device2 = new Device("Device2");
device1.openWeb("Google);
device2.openWeb("Google");
}
Device.java
Class Device{
public Device(String cap){
if(caps.equalIgnore("Device 1")){
// Initialize device1 capability and android driver 1
}
}
public void openWeb(String site){
driver.get(site);
}
}
So above code is just sample code. you can implement as per your way.
Thanks,
Priyank Shah