On the DC100, can I automatically save data to both SCSI and floppy media at the same time?

Yes. However, please note the following settings.

• Make multiple memory partitions.
• On the SET UP menu under MEM SET, set FILE COPY & DELETE=OFF, and FILE ROTATE=ON (WRITE MODE=REPEAT).
• Event actions must be set, for example:
  LOGIC BOX NO=1
  EVENT=FILE END
  ACT=EDGE/MEMORY: CP_FDD
  LOGIC BOX NO=2
  EVENT=FILE END
  ACT=EDGE/MEMORY: CP_SCSn n:SCSI ID no.

For details, see the user's manual.
User's manual