NoDuplicateLogin session tokens only available to single ZEO client

I'm working on a site that is using a modified version of Products.NoDuplicateLogin (GitHub - robinsjm2/NoDuplicateLogin: This is a fork of the NoDuplicateLogin Plone add-on that adds a number of maximum seats for a single login.) to limit the number of users able to log in under a single login. In plugin.py, it's using OOBTree() to store create user tokens on the Plugin itself. The site is using multiple client ZEO Clients and haproxy. I've noticed a session token's information only appears on the ZEO client that user logged into rather than be accessible to all of them.

Is there a way to get that information to show up across all ZEO clients?

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