Here's my code:

#!/usr/bin/perl
$tape=q
print "#!/usr/bin/perl\n\$tape=q\n$tape\n;$tape\n";
;print "#!/usr/bin/perl\n\$tape=q\n$tape\n;$tape\n";

Here's the code in action:

carfax:~> echo "here's the code in action"
here's the code in action
carfax:~> cat 6-840.pl
#!/usr/bin/perl
$tape=q
print "#!/usr/bin/perl\n\$tape=q\n$tape\n;$tape\n";
;print "#!/usr/bin/perl\n\$tape=q\n$tape\n;$tape\n";
carfax:~> 6-840.pl > output
carfax:~> cat output
#!/usr/bin/perl
$tape=q
print "#!/usr/bin/perl\n\$tape=q\n$tape\n;$tape\n";
;print "#!/usr/bin/perl\n\$tape=q\n$tape\n;$tape\n";
carfax:~> cmp 6-840.pl output
carfax:~> 

The cmp command indicates there are no differences between
6-840.pl and its output.