Are my accounts linked somehow?

So I have this account on NA, name Paero, and I made another account on oceania, with the same name.

The thing is, when I change my summoner message on one account, and then log into the other, the account I just logged into will have the same message. Ive tested this by changing it and logging in and out and noticing the other account has changed its message.

I also brought an XP boost for my oceania account to level up faster, and when I log into my NA account, I always have the message that I have run out of XP boots.

My question is, are my accounts in anyway linked (I use the same login name for each but with a different password)