[Can we utilize the Same Laptop for 2 different accounts of Fiverr?]

No you are not will be able to create a new account on the same email and same phone number 

[Finally I have completed 100 Orders]

Congratulations dear,,

[Have You Used Fiverr Sellers to Improve Your Gig?]

Rather than trying to work on everything, it is better to be experienced in one subject.