There is no feature for running two accounts, and almost every reason people want one is already solved by a single account.
You do not need a second account to sell
One account does both. Buying and selling live on the same login, and opening a store does not change how you buy. Can I buy and sell with one account?
Your store has its own name, logo and page, separate from your personal profile — so selling does not mean putting your own name on a shopfront.
You do not need one for a second shop
A store can have a team, with people added to it at whatever level you choose. That covers "my cousin helps me run it" without anybody creating anything. How to add someone to your store.
The reason a second account is a problem
You cannot bid on your own items, and a second account does not change that — it makes it worse.
Bidding on your own listing through another account is shill bidding: pushing up a price with the reserve and the other bids in front of you. It is the single most damaging thing a seller can do to a live-auction marketplace, and it is why the restriction already extends past the owner to everyone on the store's team. A member of a store cannot bid on that store.
So the one thing a second account would let you do is the one thing that gets a store closed.
The other reason
Strikes and account standing follow the person. An account created to get around a restriction on another is not a fresh start, and treating it as one is a worse position than dealing with the original problem.
If your account is restricted, the route is to find out why and appeal it. Why was my account suspended?
Two people in one household
Two people, two accounts, each their own — that is not one person with two accounts and it is entirely normal. Just do not bid against each other on the same item, which is the same shill-bidding problem wearing a family hat.
Changing what people see
If the issue is that your name shows up somewhere you would rather it did not, change the name rather than the account. Changing your display name.
More: how to create an account, how moderation works, what Metzee will not do.