Duplication of menu

Since the day I migrated my WordPress site, I have been facing this strange problems and I do know why, but don’t know how to fix it…
Earlier the table prefix of the site was xyz_ and then when i migrated, i created using abc_ as table prefix. And I didn’t notice but imported the database with prefix xyz_ into abc_. Since then I am facing strange issues. Now when i look into my db, i can see multiple tables eg xyz_posts and abc_posts. Coudln’t get my fingers to delete which one as my contents are half in xyz_ and other half in abc_. I need to make those one.

And I think the problem I am having now i.e on https://tibetanwomen.org the menu is duplicated. Even the backend to control the menu seems to be useless… Instead I can see that there is already 2menus created in English in the backend but can’t really see it.

Please help