TaxCycle looks for a client with the same email in TaxFolder. If it does not find one, then it will create a new client. So, yes, you would need to first update the client email in TaxFolder and then send your print request to ensure it gets attached to the intended existing client in TaxFolder. See: Updating Client Email and Phone Number in TaxFolder - TaxCycle for a more detailed explanation.
If you print to a deleted client, TaxCycle will alert you in the left sidebar that the client has been deleted. You would then need to restore them in TaxFolder. TaxFolder will not create a duplicate client if the email is already attached to a client (active or deleted).
The ability to merge clients is a suggestion we have on the list. You can upvote this improvement here: The ability to merge clients in TaxFolder