Having more than one sole trader business doesn’t mean that you have to register for self-employment again. If you do that, HMRC will issue you with another UTR number, and expect you to complete separate tax returns for each business. Instead, you’ll submit one single Self Assessment tax return, with a separate section to deal with each business.
I have had in the past 2 different business at same time and included all info both on one tax return.
Had limited company too and personally i prefer being a sole trader, i personally would not have a limited company for any adult business but would use it for non adult businesses depending on what it is.