The combination of one inboard and one outboard wheel on each strut makes sense to me...
Because....? Same could be said for pairs of inboards or outboards.
I don't know either, but thinking aloud; if it was inners and outers, then would the inners sense differently to the outers if there was a runway camber, whereas with one inner and one outer this would be avoided ?? (Are runways cambered? - I've never really thought about it).
Or maybe the 'one inner one outer' configuration allows for cross-wind induced weight shift effects??