Question Assign RenderTextures to Materials' property

I assign RT-A to material A, RT-B to material B, but i got RT-A on material B and RT-B on material-A (by frame debugger). I guess command buffer is execute async on rendering thread after a few frames. But texture is setted every frame on main thread. Then objects are rendered to a rt that was released to pool then get by another material.
I also tried to release tempRTs at next frame. but it didn't change anything.

note: the '_ShadowMap' temporary render texture below is a R8 mask，and light is a custom component.

Code (CSharp):

1.  
2. foreach(light of lights)
3. {
4.   var rt = RenderTexture.GetTemporary(desc);
5.   _tempRTs.Add(rt);
6.  //_cmd.GetTemporaryRT(propId, size, size, 0, FilterMode.Bilinear, RenderTextureFormat.R8);
7.   _cmd.SetRenderTarget(rt, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store);
8.   _cmd.ClearRenderTarget(false, true, Color.white);
9.   _ctx.ExecuteCommandBuffer(_cmd);
10.   _cmd.Clear();
11.   _ctx.DrawRenderers(_cullingResults, ref _drawingSettings, ref _filteringSettings);
12.   // i want to set the result to material
13.   light.Renderer.sharedMaterial.SetTexture("_ShadowMap", rt);
14. }
15. ...
16. /* Render Scene */
17. _ctx.DrawRenderers(cullingResults, ref drawingSettings, ref filteringSettings);
18. ...
19. for (int i = _tempRTs.Count - 1; i>=0;i--)
20. {
21.     //_cmd.ReleaseTemporaryRT(ShadowMapIDs[i]);
22.     RenderTexture.ReleaseTemporary(_tempRTs[i]);
23. }
24. _tempRTs.Clear();
25.