Sorry, that specific use case (automatic selection of one out of many devices attached to the same username) isn’t supported. Setting
autopush = yes would result in an automatic push to the first phone attached to the
root user, so you should not enable this option. Without autopush, the user ssh’ing in would choose their factor from a list of all devices attached to
Again, generally we see customers using sudo, and in that situation each sudo-er is an individual Duo user with their own devices.