message: use the same renaming pattern for dupe cols as ColumnList
diff: @@ -220,13 +220,13 @@ vector<string> GetUniqueNames(const vector<string> &original_names) {
  auto insert_result = name_set.insert(name);
  if (insert_result.second == false) {
  // Could not be inserted, name already exists
  - idx_t postfix = 1;
  + idx_t index = 1;
  string postfixed_name;
  while (true) {
  - postfixed_name = StringUtil::Format("%s_%d", name, postfix);
  + postfixed_name = StringUtil::Format("%s:%d", name, index);
  auto res = name_set.insert(postfixed_name);
  if (!res.second) {
  - postfix++;
  + index++;
  continue;
  }
  break;
  