Are Hellman's mayonnaise and Best mayonnaise the same exact thing?

I noticed that when I lived in the midwest, grocery stores always carried Hellman’s mayonnaise, however now that I live in LA, all I see is Best mayonnaise, but the packaging and logo looks exactly the same as the Hellman’s logo and packaging. Also, I just had the Hellman’s jingle in my head which is “Bring out the Hellman’s and bring out the best!” Which of course led me to think that Hellman’s and Best are actually the same company. If this is the case, why would a company choose to market the same product with a different name within different geographic regions (that are still within the same country)?