Clients can see each other's DBs

[Mosquito]

Me again. I've been busy today.

I have two clients -

client6 has a database named: c6wordpress
client8 has a database named: c8wordpress and c8piwik

Issue:
When client8 clicks on his phpMyAdmin link, it loads but displays the databases for c6wordpress. c8piwik is not seen.

Why can client8 see client6's MySql databases? How do I fix this?

[Mosquito]

This can be disregarded.

This particular client had registered multiple times. He had clients5-8. He logged into phpMyAdmin under his client6 account, worked in their for a while and then logged into client8. phpMyAdmin had cached the credentials for client6, so he kept logging into that instance.