For Line Rates > 1500 and when the Include Shared logic in the core is selected, there is a provision given to have the MMCM outside the core (required clock inputs must be driven to the core) by selecting the External MMCM in GUI for MMCM selection. You can use the same MMCM across different banks.
Selecting Internal MMCM implements MMCM+PLL combination in the core and the clocks can be share within the Bank only.