I just ordered an Echo and also have the Dot ..... both Echo's will be in ear shot of each other. Do you have any interference problems, or are yours better separated?
My Dot sets on my side-table next to my easy-chair (in the living room). With the TV on I can whisper to it (but I talk to it normally) and it replies fine. The Echo is 30 feet away, in the next room.
I got the Echo mostly so my wife could listen to (stream) music. It can easily be heard in the kitchen, dining room (where it is located), or even most of the main floor if turned up enough. But the wife listens to music at around level 3 or 4.... which I don't even hear when I am in the living room. BTW only one device can play music at any one time (according to the spec).
If I am in the kitchen (and cooking) I can ask (holler) for Alexa to give me a timer.
The closer Echo will ALWAYS reply. The two devices will talk to each other and determine which one is closest to me.... and that is the device that will reply and play the timer alarm. [
But because the wife keeps the volume level set low... I have to remember to assign Alexa to higher volume level].
They really don't seem to have any problem figuring out which one I am talking to. If I stand in the doorway between them and ask for todays weather forecast I will get the reply from the one I am looking... in the direction of.
I am confident I could set both in the same (large) room and get reply's from the device I look at.
These things are addictive! I am thinking about adding one in the bedroom to use as an alarm. And I wouldn't mind having one downstairs too. You know... they make wall mounts for the Dots. Maybe next time they have a price cut......