We’ve tried to replicate this issue without any success. Could you please state every step you take when you setup and add the two ‘Productlink’ widgets to a single page?
Or perhaps create a temporary page with the 2 widgets and provide the direct link.
There are several ways this might happen when you edit the page. Via copy/paste or perhaps another plugin modifies it accidentally.
You can fix it by changing the block_id so that every block has a unique id. Every created block will begin like this: