Restoring transactions within the application, getting the same transaction ID

I am currently testing sandboxed app purchases and every time I revert previous transactions my receipt includes the original transcoding ID in both transaction_id and original_transaction_id fields.

From reading Apple's documentation, I figured out that the restore is a completely new transaction (which means the new transaction ID I'm assuming). And that's why original_transaction_id is added to add information.

What I get is true_transaction_id and transaction_id on restore, is this sandbox related? Or am I getting it all wrong?