Hi, we have recently updated to the latest WP 5.9.1 and the latest ACF PRO 5.12. I have created a simple ACF block and added this to a block within an innerBlock like the standard WP Column block. I then duplicate that block within the editor and the form fields have the same id which means that any changes to the duplicated block are then changed on the original block that I duplicated from.
I tested this in two environments. Firstly with an older version of ACF PRO and the latest WP and the fields were different. I then updated ACF PRO and after duplicating a block, the field ids are the same.