Mass Copy Question

 I wanted to know how the system identifies a particular transaction for Mass Copy and checks if it is copied and or done in Tax book.

For example, you add an asset in CORP book, you can add it in tax book manually . When you run the mass copy, the addition does not get copied and you get a warning in log file .

I wanted to know how the system behaves for other transactions like say Cost Adjustment on the asset in CORP book.

What happens if I do the same cost adjustment for Tax book either through API or UI ? will the system do the cost adjustment again during periodic mass copy or give me a warning?