Same problem here. The documentation of the scrapbook says the following to this:
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NOTE: Because you're aliasing the original block, if you try to place the same block many times in the same page only the first one will actually stay when you save your changes. This is admittedly annoying problem if you've got a block that needs to be repeated inside the same page a lot. It's just the product of the way this feature has matured and not a brilliant plan you don't understand. Best advice, use the personal scrapbook for this type of problem where every block you make is a new instance.
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But using the personal scrapbook is not helping at all. The blocks there may not be global and being an instance of the original block in the scrapbook, but you STILL can just add one occurrence per site.

We want to give our clients for each project some templates on the way, for example a minitemplate for their workers (table with image on the left and Info scheme on the right. If the scrapbook could be inserted multiple times then this would be perfect. If not then I don't know how to do that without a lot of hassle.

You can't have exactly the same inserted more then once, but if you for example insert one and then make ANY change on it, then you can add another one, and so on....

Not perfect, but guess that's a workaround for some elements like news.