In the Single Candidate Portal (for all open competitions published after 1 January 2025):  

You have to fill in your CV data only once (under “My account”/”My CV”). A snapshot of your CV will be attached to your application when you validate it.  

In the EPSO account (CAST only): 

You have to create and submit a new application via your EPSO account for each selection procedure you want to apply for.