I wouldn't let my 2 walk that far together either.
I did let DS1 (then aged 8 1/2) walk the mile to school once or twce at the start of last year. But for that distance I wouldn't have been happy with them walking together that distance.
I wouldn't be happy letting them walk any further than they currently do at their current ages either - so if I'd moved 2 streets away rather than just one from the school then I would be walking DS2 every morning.