Hi,
record ID cannot be the same in different tables. Every record receive it's own ID when created, and its unique. I think, you even cannot have 2 records with the same ID in your whole company with all Workspaces and Bases.
Record ID a string recXXXX , where XXX - random 14 characters, letter or number, case sensitive. You can see it adding a field with formula RECORD_ID(). Or if you extend the record by pressing space, ID will be visible in browser address bar, after view ID.
When you set up automation, you add record_id to the respective field. If you put this id in Table2 Update record step, of course it can't exist there.
I think, you should add 'child_id' column to Table 1 with ID of record in Table 2, and add to your first automation last step after Create Record (in Table 2), the step with Update Record (in Table 1), where you put ID of new-created record in that field.
Records that already existing in Table 2, must be somehow linked to their respective 'parents' in Table 1, then you can temporary create formula field in Table 2, with RECORD_ID(), and reflect it in Table 1 via lookup. Then you can copy values to the 'child_id' field, and then delete link and lookup.
So when automation 2 is triggered, and you want to Update record in Table 2, under 'Table' field you have record ID field. Instead of putting there ID of a record in Table 1, you should put there a value of a 'child_id' field.