A farmer who farms 3,000 acres in family partnerships with two other individuals bought a second combine a few years ago when fall was late and wet, to ensure that they could harvest beans on time. The combine was identical to their first one, but had only a grain table, not a corn head.
This winter the farmer is moving up a couple series, still staying a couple series behind the newest models, including the brand new models introduced by Deere for 2012. That's how he believes he can justify ownership in two combines economically. He wants to keep trading up to get new technology, but doesn't believe he can trade all the way up to the very latest technology due to the high price of brand new models.
When he originally bought the second machine, he considered selling it after the season. However, he discovered that having a second combine to get soybeans out of the field before they over dry and while weather is good is worth keeping the second machine. He didn't run the second machine in corn because their system, at last in a normal year, is only geared to handling corn from one machine.
However, having the second combine identical to the first paid off when the first machine broke down. Instead of losing a couple days to extensive repairs, they simply switched heads and kept running while the first combine was being repaired.
The strategy has worked well enough that the decided to continue it, and traded his two older combines for two newer ones, both identical, again. And again, he will go with two grain heads and one corn head. That lets him get beans out on time, but doesn't leave a machine sitting ideal during corn harvest with an extra head on it just because corn yields more, and their grain handling system can't keep up with more than one combine at a time.
Everybody gravitates to the strategy that works for them. For this farmer, two identical combines with two grain heads and one interchangeable cornhead seems like the way to maximize available harvest days for both crops.