There are 2 System Recovery CD-ROMs included (varies depending on the model). Are both of them needed for reconfiguration? On what occasion is the second System Recovery CD-ROM (Vol. 2 of 2) needed?

There are 2 System Recovery CD-ROMs included (varies depending on the model). Are both of them needed for reconfiguration?
Under what situation is the second System Recovery CD-ROM (Vol. 2 of 2) needed?

When you reconfigure your computer, insert the first CD-ROM (1 of 2) into the CD-ROM drive and turn on your computer. (See the Instruction Manual for the detailed reconfiguration procedure.)

[System Recovery CD-ROM]

First (Vol.1of2): Common bundled applications software and utilities which are shared by the operating system (Windows) and the model are stored in this CD-ROM as an archive named Sony.pac. You can start them from this CD-ROM (i.e boot up using this CD-ROM). You can restore the computer to its original state when shipped using this disc.

Second (Vol.2of2): Applications and sample data for some models are stored in this CD-ROM. It also contains all the necessary drivers for the system. You cannot start them from this CD-ROM.

[Remarks]
Models that require the second CD-ROM for reconfiguration have the sony2.pac file in the Vol.2of2 CD-ROM.