You can't do that in scratch. At least, the way you're talking, it sounds like duplication, which isn't in scratch. A way you could do it is by stacking a couple sprites on top of each other. A more complex way to do it would be to use the stamp feature and have the sprite check every stamping spot to see what's going on there (sort of).
Offline
There's a way to create your own blocks, including Duplicating, which would give them the same script, but then everyone who viewed your project would have to make that block for it to work.
Offline
Panther (basically exactly like scratch, but advanced by some programmers) has a clone block that does that. You could try downloading that. But then you couldn't put them online on Scratch.mit
Offline