Exec vs. Exec exec

In the section on initialization in the fvwm man page (about 6% down the page), it gives a code line:

+ I Exec xterm

Later in the section covering Wait (around 85% down the page) the man page gives the code line:

+ I Exec exec xterm -geometry 80x64+0+0

I’m unclear the two types of commands used. Is it because of the -geometry switch in the second line?


       Exec command
              Executes command.  You should not use an ampersand '&'  at  the
              end  of  the  command.  You  probably want to use an additional
              "exec" at the beginning of command.  Without  that,  the  shell
              that  fvwm  invokes to run your command stays until the command
              exits.  In effect, you'll have twice as many processes  running
              as  you  need.  Note that some shells are smart enough to avoid
              this, but it never hurts to include the "exec" anyway.

– Thomas Adam