Create a copy of read-only mesh animation in Unity (by neodrop)

CurvesTransferer.cs

using UnityEditor;
using UnityEngine;

public class CurvesTransferer
{
const string duplicatePostfix = "_copy";

static void CopyClip(string importedPath, string copyPath)
{
    AnimationClip src = AssetDatabase.LoadAssetAtPath(importedPath, typeof(AnimationClip)) as AnimationClip;
    AnimationClip newClip = new AnimationClip();
    newClip.name = src.name + duplicatePostfix;
    AssetDatabase.CreateAsset(newClip, copyPath);
    AssetDatabase.Refresh();
}

[MenuItem("Assets/Transfer Clip Curves to Copy")]
static void CopyCurvesToDuplicate()
{
    // Get selected AnimationClip
    AnimationClip imported = Selection.activeObject as AnimationClip;
    if (imported == null)
    {
        Debug.Log("Selected object is not an AnimationClip");
        return;
    }

    // Find path of copy
    string importedPath = AssetDatabase.GetAssetPath(imported);
    string copyPath = importedPath.Substring(0, importedPath.LastIndexOf("/"));
    copyPath += "/" + imported.name + duplicatePostfix + ".anim";

    CopyClip(importedPath, copyPath);

    AnimationClip copy = AssetDatabase.LoadAssetAtPath(copyPath, typeof(AnimationClip)) as AnimationClip;
    if (copy == null)
    {
        Debug.Log("No copy found at " + copyPath);
        return;
    }
    // Copy curves from imported to copy
    AnimationClipCurveData[] curveDatas = AnimationUtility.GetAllCurves(imported, true);
    for (int i = 0; i < curveDatas.Length; i++)
    {
        AnimationUtility.SetEditorCurve(
            copy,
            curveDatas[i].path,
            curveDatas[i].type,
            curveDatas[i].propertyName,
            curveDatas[i].curve
        );
    }

    Debug.Log("Copying curves into " + copy.name + " is done");
}

}