It's still on my mind too and I'm in bed now!!
I'm resolved though, it IS two spurs, it just is. Certainly in every way that matters, it is 2 spurs.
The regs don't cover this. They go far enough to limit overloading of a single spur, they don't cover the possibility of putting 2 in one box because you just don't need specific regulation for that.
As for is it right or wrong to do it this way... If it's not dangerous and doesn't explicitly break regs then it's not wrong. All we have here is something a little unusual. But hey, saved on a second jb and shortened the install time too.
Just a shame an mf box wasn't used for the sake of compliance, but that's a different topic really. And a topic I have some divisive views on so maybe another thread for that tomorrow night