I don't understand how the lenses get separated from the "goggles." were they originally sold separately?
Possibly, but people also lose stuff in the 50ish years since they were sold new.
Without the goggles, they're just a regular 50'cron (although some people say they're one of the sharpest versions), focus from infinity down to 1m or so.
You can only put the goggles on when you're at minimum focussing distance, then you can focus even closer.
If you don't want to shoot macro, you don't need them (eg you might have an SLR for that).
I haven't checked properly yet whether lens+goggles goes for more than lens and goggles separately, and I don't think that they're 'matched' to each specific lens (although I might be wrong on that), if not you can easily buy/sell them later.