Assignment is not allowed because COT groupings &1 and &2 contain COT &3

What causes this issue?

You want to assign <DS:DE.CMAC_COOBGRP>COT groupings</> &V1& and &V2&
to <DS:DE.CMAC_SPPAT>appropriation</> &V4&. Both COT groupings contain
contract object type &V3&. A contract object type may only occur
once in a specific appropriation.

Procedure for System Administrators

Check the assignment of the contract object type to both COT groupings
and of COT groupings to the appropriation.
Change the assignment accordingly.

Error message extract from SAP system. Copyright SAP SE.