I could be wrong but I was always under the impression that dubbin was more a mixture of greases and oils. But I haven't used it in about forty five years. Used to put it on my Dunham's of Maine hiking boots. Then I discovered Snoseal, and always used that on my lineman's boots, and Pivetta rock climbing boots. Didn't soften the toe and heel counters.
If it were my saddle, I don't think I'd use dubbin on a leather saddle. But only because I'm not sure what's in it.