Importing constituents using the lookup ID or GUID populates all existing addresses, email addresses, and phones records for that constituent into the corresponding fields in the constituent update batch. If address standardization and address validation are turned on, there might actually be updates to those records (check the audit table). However, just as going to a constituent record > contact tab > editing an address > saving (without making a change), updates the date changed on the address record, committing a batch with an address present will update the date changed as well.