Remember now there are 4 queens in the Alice stories (Wonderland and thru the Looking Glass). Queens’ of Hearts, White and Red. One of them ended up being Alice herself. Alice at the end of Looking Glass was crowned queen after reaching the eight rank and checkmating the red king.
Number of queens in the original story doesn’t mean much because on this show they blend characters. I mean, since when has the Genie also been the Mirror, and Rumple is Belle’s Beast. In the Tim Burton version of Alice, QoH and White Queen were feuding sisters, if memory serves, so there’s every chance they could go down a similar path, or any new path, with those characters on Once.