Why does the IP location differ if I visit Wikipedia on Chrome and Firefox?

I have the IP Country Domain Flag addon installed on Chrome and the Flagfox addon installed on Firefox. Both are meant to report where the IP address of a domain name is hosted.

I understand that a single domain may have more than one IP address. But when I go to Wikipedia on Chrome, IP Country Domain Flag says that the server is located in the Netherlands, whereas if I visit Wikipedia on Firefox, it reports the server being in the US.

Why does this happen when I am using different browsers?

By the way, I am located in Australia.