Plenty of popular online communities stop their visitors from managing multiple accounts. There are many reasons for that. Plenty of trolls use sock puppet accounts to disturb online communities. Thanks to plugins such as Register IPs, you can keep them at bay. It logs the IP address used to create each account.
Thanks to this plugin, you will have an easier time stopping trolls from creating multiple accounts using the same IP. You can easily view registration date, IP address and other relevant information for each entry. For privacy reasons, you can delete this data when a user is deleted from your database.