diff --git a/components/eamxx/src/share/io/scream_io_utils.cpp b/components/eamxx/src/share/io/scream_io_utils.cpp
index 3d79184bac9..2d5e0a840d0 100644
--- a/components/eamxx/src/share/io/scream_io_utils.cpp
+++ b/components/eamxx/src/share/io/scream_io_utils.cpp
@@ -2,6 +2,7 @@
 
 #include "share/io/scream_scorpio_interface.hpp"
 #include "share/util/scream_utils.hpp"
+#include "share/scream_config.hpp"
 
 #include <fstream>
 #include <regex>
@@ -35,6 +36,9 @@ std::string find_filename_in_rpointer (
         " - filename prefix: " + filename_prefix + "\n");
     pattern_str += e2str(avg_type) + "." + control.frequency_units + "_x" + std::to_string(control.frequency);
   }
+  if (is_scream_standalone()) {
+    pattern_str += ".np" + std::to_string(comm.size());
+  }
   pattern_str += "." + run_t0.to_string() + ".nc";
   std::regex pattern (pattern_str);
 
diff --git a/components/eamxx/src/share/io/scream_output_manager.cpp b/components/eamxx/src/share/io/scream_output_manager.cpp
index 7797a0f76bd..4f35827ba3f 100644
--- a/components/eamxx/src/share/io/scream_output_manager.cpp
+++ b/components/eamxx/src/share/io/scream_output_manager.cpp
@@ -611,8 +611,10 @@ compute_filename (const IOFileSpecs& file_specs,
   filename += "." + e2str(m_avg_type);
   filename += "." + control.frequency_units+ "_x" + std::to_string(control.frequency);
 
-  // Optionally, add number of mpi ranks (useful mostly in unit tests, to run multiple MPI configs in parallel)
-  if (m_params.get<bool>("MPI Ranks in Filename")) {
+  // For standalone EAMxx, we may have 2+ versions of the same test running with two
+  // different choices of ranks. To avoid name clashing for the output files,
+  // add the comm size to the output file name.
+  if (is_scream_standalone()) {
     filename += ".np" + std::to_string(m_io_comm.size());
   }
 
@@ -667,7 +669,6 @@ set_params (const ekat::ParameterList& params,
     m_filename_prefix = m_params.get<std::string>("filename_prefix");
 
     // Hard code some parameters in case we access them later
-    m_params.set("MPI Ranks in Filename",false);
     m_params.set<std::string>("Floating Point Precision","real");
   } else {
     auto avg_type = m_params.get<std::string>("Averaging Type");
@@ -703,12 +704,6 @@ set_params (const ekat::ParameterList& params,
         "Error! Invalid/unsupported value for 'Floating Point Precision'.\n"
         "  - input value: " + prec + "\n"
         "  - supported values: float, single, double, real\n");
-
-    // If not set, hard code to false for CIME cases, and true for standalone,
-    // since standalone may be running multiple versions of the same test at once
-    if (not m_params.isParameter("MPI Ranks in Filename")) {
-      m_params.set("MPI Ranks in Filename",is_scream_standalone());
-    }
   }
 
   // Output control
diff --git a/components/eamxx/tests/multi-process/dynamics_physics/mam/homme_shoc_cld_mam_aci_p3_mam_optics_rrtmgp_mam_drydep/output.yaml b/components/eamxx/tests/multi-process/dynamics_physics/mam/homme_shoc_cld_mam_aci_p3_mam_optics_rrtmgp_mam_drydep/output.yaml
index f2408ab189a..5922c718e6e 100644
--- a/components/eamxx/tests/multi-process/dynamics_physics/mam/homme_shoc_cld_mam_aci_p3_mam_optics_rrtmgp_mam_drydep/output.yaml
+++ b/components/eamxx/tests/multi-process/dynamics_physics/mam/homme_shoc_cld_mam_aci_p3_mam_optics_rrtmgp_mam_drydep/output.yaml
@@ -120,5 +120,4 @@ Fields:
 output_control:
   Frequency: ${NUM_STEPS}
   frequency_units: nsteps
-  MPI Ranks in Filename: true
 ...
diff --git a/components/eamxx/tests/multi-process/dynamics_physics/mam/homme_shoc_cld_p3_mam_optics_rrtmgp/output.yaml b/components/eamxx/tests/multi-process/dynamics_physics/mam/homme_shoc_cld_p3_mam_optics_rrtmgp/output.yaml
index 559f5158bb6..be4bb16b95d 100644
--- a/components/eamxx/tests/multi-process/dynamics_physics/mam/homme_shoc_cld_p3_mam_optics_rrtmgp/output.yaml
+++ b/components/eamxx/tests/multi-process/dynamics_physics/mam/homme_shoc_cld_p3_mam_optics_rrtmgp/output.yaml
@@ -117,5 +117,4 @@ Fields:
 output_control:
   Frequency: ${NUM_STEPS}
   frequency_units: nsteps
-  MPI Ranks in Filename: true
 ...
diff --git a/components/eamxx/tests/multi-process/physics_only/mam/optics_rrtmgp/output.yaml b/components/eamxx/tests/multi-process/physics_only/mam/optics_rrtmgp/output.yaml
index 24e1dfbb3e7..bdda48ebe45 100644
--- a/components/eamxx/tests/multi-process/physics_only/mam/optics_rrtmgp/output.yaml
+++ b/components/eamxx/tests/multi-process/physics_only/mam/optics_rrtmgp/output.yaml
@@ -26,5 +26,4 @@ Field Names:
 output_control:
   Frequency: ${NUM_STEPS}
   frequency_units: nsteps
-  MPI Ranks in Filename: true
 ...
diff --git a/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/CMakeLists.txt b/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/CMakeLists.txt
index 973e58b7da5..62c4b6d2266 100644
--- a/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/CMakeLists.txt
+++ b/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/CMakeLists.txt
@@ -19,7 +19,6 @@ CreateUnitTest(create_vert_remap_and_weights "create_vert_remap_and_weights.cpp"
 # Run a test to setup nudging source data:
 set (NUM_STEPS  5)
 set (POSTFIX source_data)
-set (ADD_RANKS false)
 set (ATM_TIME_STEP 300)
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/input_source_data.yaml
                ${CMAKE_CURRENT_BINARY_DIR}/input_source_data.yaml)
@@ -36,7 +35,6 @@ CreateUnitTestFromExec (shoc_p3_source shoc_p3_nudging
 set (NUM_STEPS  5)
 set (ATM_TIME_STEP 300)
 set (POSTFIX nudged)
-set (ADD_RANKS true)
 set (VERT_TYPE TIME_DEPENDENT_3D_PROFILE)
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/input_nudging.yaml
                ${CMAKE_CURRENT_BINARY_DIR}/input_nudging.yaml)
diff --git a/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/output.yaml b/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/output.yaml
index e740c5cdf1f..d9b573068ae 100644
--- a/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/output.yaml
+++ b/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/output.yaml
@@ -3,7 +3,6 @@
 filename_prefix: shoc_p3_${POSTFIX}_nudged
 Averaging Type: Instant
 Max Snapshots Per File: 2
-MPI Ranks in Filename: ${ADD_RANKS}
 Field Names:
   - p_mid
   - T_mid
diff --git a/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/output_remapped.yaml b/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/output_remapped.yaml
index c75a6a862f7..26f53fbe57f 100644
--- a/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/output_remapped.yaml
+++ b/components/eamxx/tests/multi-process/physics_only/shoc_p3_nudging/output_remapped.yaml
@@ -4,7 +4,6 @@ filename_prefix: shoc_p3_${POSTFIX}_nudged_remapped
 Averaging Type: Instant
 Max Snapshots Per File: 2
 vertical_remap_file: vertical_remap.nc
-MPI Ranks in Filename: ${ADD_RANKS}
 Field Names:
   - T_mid
   - qv
diff --git a/components/eamxx/tests/single-process/mam/optics/output.yaml b/components/eamxx/tests/single-process/mam/optics/output.yaml
index 8ea3d237933..d0c27e04284 100644
--- a/components/eamxx/tests/single-process/mam/optics/output.yaml
+++ b/components/eamxx/tests/single-process/mam/optics/output.yaml
@@ -13,5 +13,4 @@ Fields:
 output_control:
   Frequency: 2
   frequency_units: nsteps
-  MPI Ranks in Filename: true
 ...