We are seeing the same issue. My help desk is blowing up with users complaining.
Clearing cookies and cache sometimes works, but only temporarily. The next day it's back to the double sign in.
Another thing that sometimes works it waiting at least 10 seconds before accepting the MFA push notification. This is far from consistent.
I should add we are using the LastPass Authenticator, not Duo. This is a LastPass problem, not a problem with your Duo implementation.