Why do some Quantum Tape drives and loaders appear as Seagate or Certance?

Updated -

Quantum purchased Certance, a spinoff of Seagate, in 2004. Depending on the age of the firmware and/or the products manufacture/release date, certain Quantum tape drives may appear as either Certance or Seagate during boot up and use. For example, dmesg may report the following:

scsi0 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev 1.3.11

         aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 67-100Mhz,
512 SCBs

(scsi0:A:0): 320.000MB/s transfers (160.000MHz DT|IU|QAS, 16bit)
   Vendor: SEAGATE   Model: ST336807LC        Rev: 0C01
   Type:   Direct-Access                      ANSI SCSI revision: 03
scsi0:A:0:0: Tagged Queuing enabled.  Depth 4

Similar information can also be found in /proc/scsi/scsi:

Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
   Vendor: SEAGATE  Model: ST336807LC       Rev: 0C01
   Type:   Direct-Access                    ANSI SCSI revision: 03
Host: scsi2 Channel: 00 Id: 02 Lun: 00
   Vendor: SEAGATE  Model: DAT    DAT72-000 Rev: A1A0
   Type:   Sequential-Access                ANSI SCSI revision: 03