you need loop inside loop or use LINQ to build the data you need from two files. for example :
string[] lines2 = File.ReadAllLines("b.bat");
string[] lines = File.ReadAllLines("a.bat");
if(lines2.Length == lines.Length)
{
var res = lines2.Zip(lines, ( a,b) => new string[] { a, b});
slv.Items.AddRange(res.Select(r=> new ListViewItem(r)).ToArray());
}
OR
listView1.Items.AddRange(lines2.Zip(lines, (a, b) => new ListViewItem( new [] { a, b })).ToArray());