#!C:/Activeperl/bin/perl.exe
use strict;
use warnings;

my @final_array=qw/test1 test2 fred/;

   #open(DOC,'sample_testing');
   while(defined($_=<DATA>)){
	   #$_.=<DOC>; <- why are you appening?
	   
	   foreach my $value (@final_array) {
		   s/$value/pagingRAC/g; 
	   }
	   print $_;
   }

__DATA__
this is a test
this line contains test1 and test2
fred bassett is a dog but I can't spell his name.


##</code><code>##

this is a test
this line contains pagingRAC and pagingRAC
pagingRAC bassett is a dog but I can't spell his name.