Sorry for my bad english and my bad explanation.
You are right, I've set an activity that power on several devices including VU+DUO at the same time, but Vu+ DUO doesn't power up.
I've set a button with PowerToggle and it works well. But if I use an activity to power on DUO, it doesn't. I see the green light of IR blinking, but no response.
If you know the Logitech configuration procedure, I've tried to modify the on/off behavior of the single divice (DUO), setting a 2 button remote, command PowerToggle for both on and off and modifying the time of impulse 1 sec for ON and 0,5 for OFF. In this case DUO powers up but doesn't stand by.
With the single button configuration and a 1 sec time, it powers up, but in stand by it gets the too long time an go in power off menu.

Is it clear now?