It's also possible the real Batgirl showed up in #4 to the group but under Choke's control but a fake showed up to the group in #5 but Choke is having their brains (except Ivy's) see her as Batgirl.
Crap, this is getting as weird as Batman's hallucinations in the Leviathan series.
Oh well another 1-2 issues and everything will be made all clear (although I thought DC promised no more multi-issue arcs in their comics post-nu52, oh well again it's totally like DC to go back on something they said all the time).
Anyway, looks like I was wrong, your probably right in some form. Interesting issue in terms of the mystery but I hope it does get wrapped up soon.