This kind of situation is frustrating. Because each post can have no more than 6 tags and each member can follow no more than 20 tags, it's desirable to standardize tags so that individual posts and members don't have to use up all of their tag allotments on redundant tags. But people's behavior doesn't allow that to happen.
The project for Jewish genealogy is the Jewish Roots project. That project follows the tag jewish_roots and asks its members to do the same. There are 69 members following jewish_roots.
With jewish_roots as the designated standard, people should not be using the tag jewish. But people have persisted in using the tag jewish, too, so we have 43 members following jewish, and (to ensure that important posts aren't overlooked) active project members like Robert Hvitfeldt are following both tags and using both tags on their posts here. If Jewish Roots leaders, coordinators, and other active members would try to get others to standardize on jewish_roots, maybe it would be possible to stop having to use both tags.
Added: The above post reflects my perspective as a G2G Moderator. To enhance the usefulness of G2G, we Moderators work to encourage the consistent use of standard tags.