Your admin users data are on the tables admin_user and admin_passwords in your Magento 2 database, you can use these commands to export and then import in your second store:

Export

$ mysqldump -p --user=username dbname admin_user admin_passwords > myAdminUsers.sql

Import

$ mysql -u username -p -D dbname < myAdminUsers.sql

Important

If you use a database prefix, don't forget to use on these commands above.