Thanks for that info. What rebuild kit were you looking at?

When I got these wheels I was told they were from a tandem. I've since found out that Suzue in fact made "tandem" hubs. I don't know what's different about a "tandem" hub, but I found out there's a Suzue tandem axle available - with a shoulder-to-shoulder of 71mm. So one possible explanation is that someone replaced that axle with one having 70mm spacing.

Another possible explanation is the one you found, which is why I'm wondering what that kit was.