Your friend's seedlings certainly look like Bamboo - and (so far at least) I certainly can't say that of my seedlings.
What mystifies me is - if mine are something else, how 6 of them got into every one of the 6 grow cubes in the same box, when I thought I was planting nothing but Fargesia n. seeds. Curiouser and curiouser, eh?
I guess all I can do now is wait & see what they grow into. I'll post more pictures as time passes, though I guess they won't grow much bigger this year, now that summer's over.