Management and Overheads refers to a unit costs of 1'200 Euro per person month. It is up to the consortium to decide how these unit costs shall be distributed among the consortium members.
It is recommended to discuss this cost distribution during the set-up of the proposal and not to wait until the start of the project. Additionally, it is smart to fix the rules in the Consortium Agreement.
However, best practice examples very often show that the Management & Overhead unit costs are distributed according to the respective person months a beneficiary has. Sometimes the greater share of the Management & Overhead unit costs of each beneficiary are kept by the coordinator, but this can of course vary due to the different needs of a consortium.