iCloud mailbox appears twice on my Mac running macOS 15.6.1

I checked mail accounts and internet accounts for duplicates but there are none. One icloud account says read only. All the folders are the same. I recently used up all my icloud storage and wondering if 2 icloud mailboxes with all those folders is causing the overload. Sequoia.15.6.1 I don't need or want 2 icloud mailboxes.

[Re-Titled by Moderator]

Original Title: Icloud appears twice on my MAC