I am new to magento and I have multi store setup in magento 220.127.116.11 where I have retail and Wholesale website setuped. There are data on Wholesale website where user can login and see products. Product prices are set as per users, i.e. If user A login then he see different price and if user B login then he see defferent price then user A.
You don't have to copy userdata to other website.You can share customer data globally in magneto.Then if customer register any of the store can have access to login any store with same details.
To enable this go to:
admin panel > system > configuration > customer configuration > Account Sharing Option > Share Customer Accounts > Global