Ufer grounding with multiple systems
You only need 1 Grounding Electrode System no matter how many services, systems, or tenants you have in your building

All the grounding electrodes in a building are required to be bonded together to form a single grounding electrode system for the building, as per NEC 250.50:


  250.50 Grounding Electrode System. All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are
  present at each building or structure served shall be bonded
  together to form the grounding electrode system. Where none
  of these grounding electrodes exist, one or more of the
  grounding electrodes specified in 250.52(A)(4) through
  (A)(8) shall be installed and used.
  
  Exception: Concrete-encased electrodes of existing buildings or structures
  shall not be required to be part of the grounding electrode system where
  the steel reinforcing bars or rods are not accessible for use without
  disturbing the concrete.


Furthermore, NEC 250.58 requires that all services feeding a structure use the same grounding electrode system:


  250.58 Common Grounding Electrode. Where an ac system is
  connected to a grounding electrode in or at a building or structure, the same electrode shall be used to ground conductor
  enclosures and equipment in or on that building or structure.
  Where separate services, feeders, or branch circuits supply a
  building and are required to be connected to a grounding electrode(s), the same grounding electrode(s) shall be used.
  
  Two or more grounding electrodes that are bonded together
  shall be considered as a single grounding electrode system in
  this sense.