There should be three layers of scratch - foreground, normal, and background. While on one layer, a sprite won't be affected by anything on another layer. There should also be a Universal layer, which is every layer at once. Foreground goes on top of normal and background, and so forth. Figure the rest out yourself.
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You don't need it. You can use different blocks.
[blocks]
<go to front>
<go back( )layers>
[/blocks]
You can use a sprite to go different layers already!
Anyways, it will confuse new users.
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