Taking ideas from Grandfather's code, and some ideas of my own, I have made some changes to your code that should work. I commented some lines you had and replaced them with new code. Mainly the biggest change was postponing the check for a missing average (and assignment of 0) until the printout part of the code (at the end) :-)
Chris 
#!/usr/bin/perl
use strict;
use warnings;

my %usage;
my $files = 0;

for my $file (qw/sfull1ns.dat sfull2ns.dat sfull3ns.dat/)  {

    open (my $fh,'<',$file) or die "Can’t open file $file: $!";
    
    while (my $line = <$fh>) {
        
        next if $line =~ /^Server/;
    
        #chomp($line);
        #my ($server, @data) = (split(",",$line));
        
        # Assigns the first 2 values in the CSV
        # and discards the rest
        my ($server, $avg) = (split(",",$line));
        
        
        #if ($data[0] lt "!" )  {
        #  $data[0] = 0;
        #}
        
        #next if grep /[^0-9.]/, @data;
        
        #$usage{$server} = [] unless exists $usage{$server};
        #push @{$usage{$server}}, 0 while @{$usage{$server}} < $files;
        #push @{$usage{$server}}, $data[0];
        
        # if this is a second occurance of a server in the file,
        # its avg won't be assigned because the first one is already
        # stored there
        $usage{$server}[$files] ||= $avg;
    }
    continue {
      $files++ if eof;
    }
    
    close $fh or die "Can’t close file $file: $!";
}

for my $server (sort keys %usage) {
    
    #Either this server has an average (for each element of the array)
    # or assign 0 to the ones that don't have a value
    my @avgs = map $usage{$server}[$_] || 0, 0..$#{$usage{$server}};
    print join(",", $server, @avgs), "\n";
}

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In reply to Re: Eliminating Duplicate Lines From A CSV File by Cristoforo
in thread Eliminating Duplicate Lines From A CSV File by country1

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