Anyone Aware of a Plugin for Sharing Users Between 2 Standard WP Installs on Same Domain?

Hi all,

I have two separate standard WP installs, one at and one at Multisite is not an option in this setup.

I would like to share one user table between both installs. Is anyone aware of a plugin to do this? All I can find in researching so far involves editing the wp-config and core or a plugin that hasn't been updated in awhile.

I'll keep looking but thought I'd ask here in case anyone else is doing anything similar with a plugin I'm not aware of..