You CAN use the same phone to control two or more WM100's ...not easy, but dooable.
The trick is to take photos of the QR codes on each WM100 and print them out.
Once you set up the WM100's in multiple locations, the process to switch between WM100's is;
Start the WM100 app
If the app connects with the current device, or "times out"
Tap "Setup"
Tap "Reset to Factory Settings"
Confirm the "Warning" by Pressing "OK"
Select "Connect to an Existing HUB" (assuming that it's already been setup)
NOTE! If you select "Connect to an Existing HUB" the data on the current hub WILL NOT BE ERASED!
Tap "Scan QR"
Scan the QR Photo for the desired WM100
Select "Sync Data from the WiFi Hub
One note... if the WM100's are not in the same timezone, you will need to set your phone's time to the timezone where the WM100 is located... for example, to remotely control devices in a different timezone.
Suggest keeping 1.5" square photos of each WM100 clearly marked as to which device they control with you. Even if you have them someplace such as google photos, you will not be able to use them to switch between devices unless you are able to bring the desired photo up on another device for the "Scan QR" step.
Hope that this information is valuable,
Beverly Howard