Yes, has 3 other film SLRs. but I wouldn't say they are backup, but rather used for different purpose like FF capability (I don't own any FF DSLR). Also film gives a different feel to a pic. Last but not least, sometimes when I am just in the mood for film rather then digital. Nostalgic bug bite me perhaps.:bsmilie:
Ya normally use one dslr with long zoom and other with wide zoom on. I can cover from 12 - 120 or 17 - 200 depending on what lenses I mount on the dslr. Usually its 17-35 and 70-200. Alternatively it is 12 -24 and 24 -120. Occasionally in dim light conditions I will carry 50 1.4 and the 12-24. So 2 dslr are necessary. Of course I'm referring to the lens range, u need to consider the 1.5x factor for the dslrs.
The old film SLR is not really a backup body I guess, but just a camera that I use for a different kind of photography...specifically ultrawide shots and street, however I don't know how long it's going to be around. Sometimes I do debate the value of having a second system around when a separate digital compact would probably do a good job as well.
Tried it once when I managed to borrow a 2nd body. Main is 18-200, the other is 85. Aside from feeling kiasu (my own insecurity), it is really great compared to changing lens. But my main body date is 3 days behind (wrong date) so had a hard time renaming to follow chronology.