Conflicting Apple IDs between business and personal accounts on iPhone and iPad

We are talking some years ago now when all was new (and I am certainly not tech savvy). With my first iPhone I set up an Apple ID using my business email address as my Apple ID. Inexplicably I then set up a new iPad with a different Apple ID, my personal email. I am not sure how but on both my iPhone and iPad the account name associated is my original business email, yet when I try to log in on the AppleID website I can only see my newer personal log-in. On the website, when I try to log in as my original business username, and reset the password, the system seems to find my newer log-in. I am so confused and don’t know what is attributed to my newer account and older one. I really do not know what to do for the best.

[Re-Titled by Moderator]

Original Title: Account Mix-up