Duplicate VisitorID for different users


When two users access from different PCs (same IP address, browser and OS), the same VisitorID is issued. What is the cause?
Is there any other way to deal with it?

I have read the following articles.
https://matomo.jp/tech/66-ip-アドレスの代 %E3%82%8F%E3%82%8A%E3%81%AB%E8%A8%AA%E5%95%8F%E8%80%85-id-%E3%81%AE%E3%82% AF%E3%83%83%E3%82%AD%E3%83%BC%E3%81%AB%E5%9F%BA%E3%81%A5%E3%81%84

I expected a different VisitorId to be issued.

Piwik version is 2.15.0.


Hi @hammock-sato
I suggest you update Matomo to a more recent version, as 2.15 is quite old (8 years old).
Then If you use the same user information (IP, browser, OS) but no cookie nor user ID, Matomo server won’t have other choice than attributing the same visitor ID…

Hi @heurteph-ei

Thank you for answering!

I’m thinking of setting trust_visitors_cookies to 1, but what is the impact if the access source is not the intranet?

Hi @hammock-sato
I think so:

Hi @heurteph-ei

Thank you for giving me the link.

I’m thinking of changing the trust_visitors_cookies setting to “1”.
What happens to VisitorIDs that have already been issued?
Do I need to delete cookies after changing settings?

Hi @hammock-sato

I think that they won’t be used anymore… as visitor ID in cookies should be used instead.

I would say no, but this has to be tested live :wink:

Hi @heurteph-ei

I accessed the site after changing “trust_visitors_cookies” to 1 (IP address, OS, and browser settings are the same, but the OS user is different), but it is linked to the already issued Visitor ID. Is this by design?
Is there a way to have a different VisitorID issued?

Hi @hammock-sato
What id you delete all cookies from the client side?