Two Duplicate Email Inboxes & Folders In Wrong Places

Refer to screen shot for visual: Something I can't explain happened to one of my Att email accounts that somehow created duplicate Inboxes and split folders & their contents between the two inboxes.  Really weird is that a "Folders" header sits above one of the inboxes as does a smattering of folders.

The contents of the two inboxes are identical, but one has a direct subfolder that the other does not.  

This phenomenon appears in the  ATT/Yahoo webmail site (where the screenshot was taken), and in my native iPhone email.  This particular ATT email account is shared by both my wife on her iPhone and I on my iPhone.  We have not had any issues in the past with us sharing this same email account.

I have soured the internet for like issue without success and will be very appreciative of assistance in finding a fix.