It appears the Help->Tools->Remove Redundant Generated Passwords isn't working. I've noticed this periodically through the past few Mac betas. The only complicating factor I can think of for this particular instance is the generated password and resulting redundant login were created using 1P Windows beta 6.3.370.
Can anyone confirm whether the clean-up is broken in general, or if we're dealing with a cross-platform beta anomaly? If the latter, I will follow up with the Windows beta folks.
1Password Version: 6.6.BETA-10
Extension Version: 126.96.36.199
OS Version: 10.12.3
Sync Type: Families, Teams