Technically you will both need to setup an account with Epic for the UE4. But, from what Epic suggests…you can setup one account, then deactivate it. It allows you to download the engine, etc. BUT if you deactivate it you just don’t get future updates like if they go to 4.2, etc unless you reactivate the account.
So you could setup one, download and then deactivate (pay $19) Then when you have another $19 activate the second account. You will both have it for $38 and then if you ever need to update like a major change, etc. that will help you just reactivate your accounts for another $38 and you are good to go.