RequestListener behavior when using thumbnail() method

I'm using Glide 4.12.0 (latest version).
When I start downloading an image with `thumbnail()` specified like this

`requestBuilder.thumbnail(thumbRequestBuilder).load(mainUrl)`

**I.** If the main request fails before thumbnail request finishs and succeeds we will get 2 `RequestListener` callbacks in this order:
1> `onLoadFailed` for the main request
2> `onResourceReady` for the thumbnail

I think this is redundant and Glide should wait for the thumbnail request to finish and call either `onLoadFailed` if both request fail or `onResourceReady` if thumbnail request succeeds.

**II.** If both thumbnail and main request succeed and thumbnail request comes first we will get 2 `onResourceReady` callbacks. This is ok but look like there is no way to check which is thumbnail and which is main request.