GET API /TDMModelService/api/ca/v1/datamodel/information will will just return the latest datamodel of a portal version even if it has more than one datamodel.
CA TDM 4.11.89.0
The API is working as designed, it will bring back the latest Model only.
If you want the detail of a specific model you need the JobID associated with the Model.
API "/TDMModelService/api/ca/v1/datamodel/models" helps you to get all of the datamodels of a version.