Hello @Haribo,
What is happening is the following, I presume you have installed Filebeat from one of the packages.
When you run sudo filebeat -e it executes the bash script in /usr/bin/filebeat which spawn filebeat with the correct options to setup the environment, this will result in 2 different processes.
So in your case, It is normal to have 3.
The last line is a filebeat that was started from an init script