Do I need two Arlo apps on phone to monitor two different accounts?

[JamesC]

CFrost,

No, You can log in to any Arlo account using the Arlo mobile app as long as you know the credentials.

JamesC

[jguerdat]

Also, you can grant one of your email addresses access from the other account using Settings, Grant Access. That way you can monitor both systems from one login. Otherwise, you have to log out from one account and log in to the other.