regex duplicating literal part of replace string

[joseph@…]

The below code should result in 'moreless' but instead results in 'morelessless'

#include <iostream>
#include <string>
#include <boost/regex.hpp>

int main(int argc, char **argv)
{
  boost::regex::flag_type regex_flags = boost::regex_constants::normal;
  boost::regex_constants::match_flag_type match_flags = boost::regex_constants::match_default;
  boost::regex pattern("(.*)", regex_flags);
  std::string strResult;
  strResult = boost::regex_replace(std::string("more"), pattern, std::string("${1}less"), match_flags);
  std::cout << strResult << std::endl;
  char result;
  std::cin >> result;
  return 0;
}