I have registered a Gutenberg block using the "registerBlockType" function. Within that function I declare attributes for the block like so:

registerBlockType( 'myblock/myblock', {

    attributes: {
        seed: {
            type: 'string'
        },
        compositionData: {
            type: 'string'
        }
    },
    {other wordpress related settings...}
});

I then pass the attributes into my edit function, and edit them as such:

function Edit( { attributes, setAttributes  } ) {
    setAttributes( { seed: 5 } );
}

This all works as expected and attributes.seed is now my random number (assuming I update the post).

The problem however is if I have 2 of "myblocks" on the same post/page, whenever I edit one of them, the other gets edited also. So they will always both share the same seed, and I have no way to differentiate them.