What is the determined dower if the specification of the co-wife's divorce is voided?

Primary text

If the specification of the divorce of the co-wife as dower is ruled invalid, the wife is entitled to her customary dower (mahr al-mithl). Alternatively, if the husband divorces her before consummation, she is entitled to half of the customary dower or a consolatory gift (mut'ah) according to those who mandate compensation for void stipulations.