fixes duplicate variable declaration and templates

src/main.cpp

@@ -71,7 +71,7 @@ int main(int argc, char *argv[]) {
         ("elf,f", po::value<std::vector<std::string>>(), "ELF file(s) to load")
         ("mem,m", po::value<std::string>(), "the memory input file")
         ("plugin,p", po::value<std::vector<std::string>>(), "plugin to activate")
-        ("backend", po::value<std::string>()->default_value("interp"), "the memory input file")
+        ("backend", po::value<std::string>()->default_value("interp"), "the ISS backend to use, options are: interp, tcc")
         ("isa", po::value<std::string>()->default_value("tgc_c"), "isa to use for simulation");
     // clang-format on
     auto parsed = po::command_line_parser(argc, argv).options(desc).allow_unregistered().run();