There is no need for two wing anti-ice P/Bs, because you would NEVER want - or need - to anti-ice just one wing and not the other
So there is simply no need for two switches, which would only add needless complication and no advantage whatsoever.
Having two wing anti-ice switches could also cause a serious problem if both wing anti-ice switches were pushed but only one actually stayed in, and this was not noticed until one wing stalled. Or if one switch became faulty.
You really don't want asymmetric lift.