Onion resurrection!

Hi all

I harvested my onions last July/August but obviously missed some as I've got a fair few doing very well now!  I started to pull them out assuming they're into their second year and hence flowering, which usually means hardening of bulb and stem I think?  I then wondered whether I'd slipped up: anyone left their bulbs in for a second year (planted last March) and had any success?  They're Sturon or Stuttgart I think.