エディタ拡張書いたの初めてなので記念に
ただの供養です

using UnityEditor;
using UnityEngine;
using System.Linq;
using System.IO;


/// <summary>
/// 指定したオブジェクトをコピーするやつ～
/// </summary>
public class CopyWizard : ScriptableWizard
{

	public Object copyBaseAsset;
	public string baseName = "";

	[Multiline(20)]
	public string createNameList;


	private Object prevObject = null;
	[MenuItem("Custom/Copy")]
	static void Open()
	{
		DisplayWizard<CopyWizard>("一括コピー");
	}

	void OnWizardUpdate()
	{
		if (prevObject == copyBaseAsset) {
			return;
		}
		prevObject = copyBaseAsset;
		baseName = copyBaseAsset.name;
	}

	void OnWizardCreate()
	{
		var path = AssetDatabase.GetAssetPath(copyBaseAsset);

		var extension = Path.GetExtension(path);
		string dirPath = Path.GetDirectoryName(path);

		var list = createNameList.SplitLine().ToList();
		list.RemoveAll(str => {
			return str.IsNullOrEmpty();
		});

		for (int i = 0; i < list.Count; i++) {

			string fileName = baseName + list[i] + extension;
			fileName = fileName.Trim();
			string createPath = Path.Combine(dirPath, fileName);
			AssetDatabase.CopyAsset(path, createPath);
			AssetDatabase.ImportAsset(createPath);
		}
	}
}

BaseName + CreateNameListの改行で区切った分データができます

material_001 ~ 008まで　できるよ