Would know roughly what era this would be from aprox?
I'm not sure of the earliest date for soldering coppers, but I imagine pretty darned early. They're still being made and sold.
Soldering is still, in my opinion and that of many other folks, still the best way to join metal in certain applications, such as architectural flashing (e.g., roof flashing, caps above exterior window and door trim, and the like). A soldering copper or two with a propane-powered "stove" to heat the copper(s) allows the mechanic to solder the work in the field in places where electricity isn't available or is hard to get. On a lot of building sites, if there is electricity, the carpenters want to hog all the outlets/there aren't enough outlets.
When you're working that way, you want two coppers, ideally of the same size/weight/shape. One is heating while you're running joints with the other; when the one in hand gets too cool, you trade off.
Unless you're doing that kind of work, though, coppers are of limited usefulness.