Rio Grande Valley, CFI,CFII
The general reason for operating a two-locomotive consist 'cabs out' is that reversing direction of a consist simply involves running around the train at the destination -- no need to wye either the train or the consist. This is a common reason for double-cab locomotives -- you can think of the two-unit combination as "one" long, articulated double-cab locomotive.
Running elephant-style, as Balt noted, allows the train to proceed with normal control if the lead unit fails. This presumes the locomotive is actually removed from the train and not just taken off the line. Note however that the consist or power will have to be turned at the terminal location, which involves a table or wye connection.
So far, I think it is relatively rare that a consist with a cab car or cabbage on the 'far' end has more than one locomotive. It would not matter which way the non-leading locomotive(s) in such a consist were oriented, except insofar as removing the leader exposed a functional driving cab pointed in the direction of travel...
As long as both locomotive perform their intended functions there is no difference. The fun can start if and when one of the locomotives fail in some aspect of their operations. Is it the first unit or the second unit? Can the first unit still operate as a Leader even with its failure? If the first unit is no good as a leader, if the second unit is facing forward, then it may be possible to switch each engine's location in the consist. If the second unit is facing the rear, the term SOL comes into play.
Never too old to have a happy childhood!
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