yeah, sharing current is most likely the reason. It does have it's drawbacks though such as 1 diode becoming faster forward biased and taking all the current on itself momenterally enough to go poof.
Perhaps they are in parallel, but not connected with the same polarity. Think of a use for that ( hint there is at least one, I do not promise that it is great ). <= thinking regular signal diode. And could the diode be an LED, a zeener or a tunnel diode, or a.....