Sector,Total Number of Occurrence
sector1,12
sector2,30
sector3,100

House,Total Number of Occurrence
B12,80
A2,87

Sector,Total Number of Occurrence
sector 99,89
sector 11,9

House,Total Number of Occurrence
Q11,22
Q22,67

Sector,Total Number of Occurrence
sector1,12
sector2,30
sector3,100
sector 99,89
sector 11,9

House,Total Number of Occurrence
B12,80
A2,87
Q11,22
Q22,67

Sector,Total Number of Occurrence
sector1,12
sector2,30
sector3,100

House,Total Number of Occurrence
B12,80
A2,87
sector 99,89
sector 11,9

House,Total Number of Occurrence
B12,80
A2,87

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class SummarizeReport1
{
   static ArrayList<String> list1 = new ArrayList<>();
   static String line1;
   public static void main(String[] args) throws IOException
   {
        List<Path> paths = Arrays.asList(Paths.get("C:\Users\user\Desktop\Axway email\log\backup\report12017-10-31.csv"), Paths.get("C:\Users\user\Desktop\Axway email\log\backup\report12017-10-31 - Copy.csv"));
        List<String> mergedLines = getMergedLines(paths);
        Path target = Paths.get("C:\Users\user\Desktop\Axway email\log\backup\SummarizedReport1.csv");
        Files.write(target, mergedLines, Charset.forName("UTF-8"));
    }

    private static List<String> getMergedLines(List<Path> paths) throws IOException
    {
        List<String> mergedLines = new ArrayList<> ();
        for (Path p : paths)
        {
            List<String> lines = Files.readAllLines(p, Charset.forName("UTF-8"));
            if (!lines.isEmpty()) {
                if (mergedLines.isEmpty()) {
                    mergedLines.add(lines.get(0)); //add header only once
                }
                mergedLines.addAll(lines.subList(1, lines.size()));
            }
        }
        return mergedLines;
    }
}