Why will voters cast multiple votes in Maha civic polls, except in BMC?

In Maharashtra civic polls, voters in 28 municipal corporations outside Mumbai are casting multiple votes under the multi-member ward system. Each ward elects three or four corporators, requiring voters to press the EVM button for each seat. Mumbai alone uses the single-member ward system, so each voter casts one vote. Thane, Navi Mumbai, Nashik, and Pune follow the multi-member system.