Sven, I'm sure they did... Some of the oldest Hubbell stuff I've gotten are recept that I changed out of my aunts 1921 cabin east of San Diego.. I'm pretty sure they're original (T slotted) The lamp to recept socket is actually some type of ceramic.. I don't think it's porcelain, but it's definitely not plastic or bakelite... I found that in a late 40's house in the garage, running the garage door opener.
It "looks" older than the house I found it in...
-Randy