thank you for sharing your question with the Wefugees Community!
The reason why you are confused is probably because there are in fact two different things: One is called "Folgeantrag" and is probably what you meant, the other one is a "Zweitantrag".
The Folgeantrag applies for people who went through asylum procedure in Germany and received a negative result. The Bundesamt (BAMF) will review the asylum case. But it can only have success if there has been a change of facts or the legal situation or if new proof appeared for something the applicant has told in his earlier asylum procedure. A change of facts can f. e. be that the situation in the home country has changed or in the situation of the applicant.
The Zweitantrag can be filed by someone who went through asylum procedure in another EU-Country (or Norway and Switzerland) and received a negativ result. If Germany decides that it is responsible for the asylum claim, the BAMF as well reviews if there has been factual or legal changes etc. that would lead to another result.
I hope this is helpful and feel free to get in touch if you have any more questions!
All the best