You can include as many addresses, phone numbers, email addresses, credit card details etc for any contact from the contact screen. This is handy to store alternate information such as an address that is valid at a particular time of year, etc.
For example, some contacts may want you to send invoices and catalogues to their home address but use another address to ship parcels to. In this case you enter both addresses and set the one to be used for any given purpose as the default. Use the Edit/Select Alt Address command to enter new addresses, set the default or to modify an existing non default address. When you change the default the new default is displayed on the Contacts screen.
This applies to several other items as well such as the phone and fax numbers, email address, etc.