Thread:Project:Support desk/Preventing Spammy User Accounts

I see the following in the recent changes and user creation log pages on on my wiki:



The person who registered on April 29 seems like a real user. However the person who registered on April 30 seems like a spammer. Could someone explain what the bracketed item means. Does it mean that he registered with that exact username [Chaosneo45; Chaosneotix] It seems to have created 2 user accounts. Is this normal? Do you think it's spammers?

If it's spam is there anything I can do to prevent it? I already use a captcha when someone registers asking them "What is the opposite of North?". I also have Bad Behaviour and Spam Blacklist installed.