Im going to go out on a limb, and make an assumption that files are the only files in said directory, and that 'full' will only occur around the beginning of a line. With that said

#!/usr/bin/perl

use strict;

my $data   = '/path/to/base/dir';
my $multi  = '/path/to/multi/full/dir';
my $single = '/path/to/single/full/dir';

opendir(DATA, $data) or die "Cant opendir $data: $!\n";

for ( grep !/^\./, readdir(DATA) ) {
   my $in = "$data/$_";

   open(IN, $in) or die "Cant open $in: $!\n";
   my $count = grep /^(?:\s+|)FULL/, <IN>;
   close(IN);

   if ( $count >= 2 ) {
      rename($in, "$multi/$_") 
         or (warn "Couldnt move $_ to $multi: $!\n" and next);
   
   } else {
      rename($in, "$single/$_")
         or (warn "Couldnt move $_ to $single: $!\n" and next);
   }
} # END for grep
closedir(DATA);
[download]

Edit: added test for success on rename :P..