Pair of cast iron horse plaques, do they have a particular function? Age?

Hi all! I got these from an auction last year and am only getting around to posting them now. They are cast iron with a hole on either side, 7.5" across. What do you think they would have attached to? Any idea of age? Thanks for any suggestions/info!

 

Maybe vent covers?

 

I'm not familiar with that kind of thing and would appreciate being educated.
What kind of vent cover doesn't have some sort of perforation for airflow?

It does look like the back of the one on the right of the last photo was exposed to a heat source.

 

Flue covers, not vent covers. In the summer, you'd put them on the hole in the wall where the stove pipe went. We had them. I still have one somewhere in the attic.
However... flue covers were usually tin. I'd say these were decorative pieces that went on something substantial, not a wall.