Duplicate Title / URL on search engines

[grafityx]

Dear everyone,

I have serious issue with all my websites hosted on VestaCP, all are hosted on the same VPS and use different IP address (5 websites per IP).

The issue :

I see some unwanted URL that are from another website hosted on my server, example I have two websites dog.com and cat.com
When I make a search on google "site:dog.com"
Some URL will appear like this:
www.dog.com/url-of-cat-website/

When I click on it I got an 404 error.

Sometimes it's happened also with the homepage that's not using is original title, and is listed on google as :
TITLE OF THE DOG WEBSITE
WWW.CAT.COM

By the way, all my websites have their own user and FTP details in VestaCP panel, but it looks like google mixing all my websites content together.

I never get this kind of problem before with Cpanel ... How I can fix this issue on VestaCP ?

Thanks

[xorro]

Your websites seems to be hacked.

[grafityx]

Your websites seems to be hacked.

I don't think there are hacked, all the websites working fine and don't have any unwanted content. All the issues concern my own domain names. It looks more about a mistake into server configuration but I don't know what ...