Okay, as I have gone off very emotionally on this on Twitter, Tumblr, and--in the meanest thing I've ever sent to someone personally--over email, I may as well bring the rational point that just barely got brushed onto for my blog.
The big problem of a dual Batgirl setup is John Stewart Syndrome.
Notice how, when Hal came back they promised they had BIG PLANS for each of the Lanterns... And Kyle and Guy got a mini, and Hal and John would get the JLA. And Kyle and Guy got great interaction in the mini.. And he got one storyline, then Hal was the lantern for the last storyline of JLA... which was rebooted as Justice League with Hal?
And then, Kyle got a maziseries and Guy led the Corpsbook and Hal led the corebook but John pretty much disappeared?
Then after the Sinestro corps War where Kyle and Guy shared the spotlight with Soranik, and Hal got the corebook, and John got his paperwork again?
This is not because John Stewart is a bad character. On the contrary, he's a fucking great character. He has been strong since his first appearance, and distinctive as a thinker/activist from Hal and Guy and now Kyle.
But John, despite having been given the mainstream paly with the cartoon most recently (and Hal is now getting the movie), is almost never used. Even now in GLC he's basically a bondage king while Kyle and Soranik lead the mainplot. He is constantly, despite the promises and attempts to the contrary, downplayed for other Lanterns.
This is what would most likely happen in the event of two Batgirls. Endless frustration as Cass is pushed to the side for Steph. I can be an optimist, and a pessimist, but here I am being a realist. It's cynical, and it's a wrong in itself that should be fought but this is the most realistic result of a campaign for two Batgirls rather than a campaign for the return of Cass to Batgirl.
So yeah, gonna resist this suggestion, guys. It's a lovely thought and I'm sure you have the best at heart, but it is not a good option.