I am using the Fiverr website on Computer Desktop and my brother on the laptop and we have the same internet wifi. But my brother is working in a totally different niche. I am in WordPress and SEO and he is in lead generation, cold calling. It is safe to work. We are working differently.
Yes, as long as you offer different services.
However, it is always safest to contact CS and explain your situation. Fiverr could notice that you both have the same IP address and ban you both, thinking you are one user with two accounts.