Characteristic & already exists under this node

What causes this issue?

You have tried to move to a characteristic to a node, that already
exists under this node.
A characteristic is only allowed to exist once under a node.
With intervals a check is also made as to whether a characteristic
falls in the interval range or whether the characteristics overlap
directly.

System Response

The processing was terminated.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.