Sad Irons and Trivets

I chose these from my mother's estate and don't ever remember her NOT having them. (I am now 54 years old - she would be 96.) While just putzing around and googling them, I found it odd that there are so many trivets and so few sad irons. Is it unusual to have a set, or are they not really part of a "set" per se, but pieces that were sold separately?

While preparing to take the pics, I noticed there was more than a respectable accumulation of dust so that it looked almost like fuzz. SHAME ON ME, I know . . . But I didn't want to scrub or take too strong of a hand to them for fear of taking the paint off as well. After getting off the little bit of dust I did, I was reminded how pretty I think they are and that I should find a better spot to display them than on a dusty bookcase.