print comp( 'foo', 'ofo' )     ? "True\n" : "False\n";
print comp( 'foo', 'foo' )     ? "True\n" : "False\n";
print comp( 'abcde', 'bacde' ) ? "True\n" : "False\n";
print comp( 'abcde', 'cabde' ) ? "True\n" : "False\n";


sub comp {
  my($x,$y)= @_;
  my($xreg)=join('|', grep $_,map {$1.$3.$2.$4 if $x=~ /^(.{$_})(.)(.)
+(.*)/ && $2 ne $3} 0..length $x);
  return $y=~ /^$xreg$/;
}
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Update: Forget it ;-/ Abigail's is MUCH better! ++ for her him

Update: Thanks to dragonchild and perlguy for telling me that Abigail-II is a he ;-)