Something isn't right. A concatenated calculation which uses only values within its own table will display the same results in ANY of its table occurrences. A table occurrence is just another representation of the table; they must match because they are the same table.
Can you provide a file (upload to free share site)?
A simple "oops" that might explain your issue.
When you are on your layout that refers to the "other TO", make sure that references to this field refer to the correct TO as well as the correct field or your reference to that field could return null or even a completely incorrect value from another record in the same table. This can be an issue for fields you add to this layout. It can also be an issue for script steps of a script that executes when this layout is the current layout.
oops. You are right. Thanks again for your insights!