use strict;
use warnings;

my (@config);
push @config, 'line 1 oldtext appears but once here',
              'line 2 oldtext is here twice oldtext',
              'line 3 oldtext is here oldtext three oldtext times!';
for (@config) {
   my $count = 2;
   while ($count-- && s/oldtext/newtext/) { print 'Replaced '}
   print "\n";
}

print "$_\n" for @config;