Customer with two email addresses and 1 phone number, cannot have the same phone number on both

I have multiple customers who have registered a business and a home email, they have been ordering from both. I need to have the same phone number on both accounts, when I try and update the data for them it gives me a duplicate phone number failure.

How can this be done, can the accounts be linked, can I have two emails on one account instead? I.e can they be merged but have both email addresses be available to use and send newsletters to etc

Bonjour je passe par cette plate-forme pour une meilleure collaboration dans le secteur de l importation des voitures d’occasions de tout type 0022955005265 mon WhatsApp mon mail daraaliou05@gmail.com