Because some priorities are only partial priorities, that is, only partial references to the parent case;
Therefore, if the parent case is C, patent document A claims partial priority of C and patent document B claims complete priority, then patent documents A and B are not exactly the same.
But what is certain is that the ideas of the two schemes should be the same, but there may be differences in specific implementation.
So, by reading A, you can also know what B wrote.
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