diff --git a/src/spikeinterface/benchmark/benchmark_merging.py b/src/spikeinterface/benchmark/benchmark_merging.py
index a1085455fe..83d85a4243 100644
--- a/src/spikeinterface/benchmark/benchmark_merging.py
+++ b/src/spikeinterface/benchmark/benchmark_merging.py
@@ -158,7 +158,7 @@ def plot_potential_merges(self, case_key, min_snr=None, backend="ipywidgets"):
 
         plot_potential_merges(analyzer, mylist, backend=backend)
 
-    def plot_performed_merges(self, case_key, recursive=False, backend="ipywidgets"):
+    def plot_performed_merges(self, case_key, backend="ipywidgets"):
         analyzer = self.get_sorting_analyzer(case_key)
 
         if analyzer.get_extension("spike_amplitudes") is None:
@@ -167,18 +167,18 @@ def plot_performed_merges(self, case_key, recursive=False, backend="ipywidgets")
             analyzer.compute(["correlograms"])
 
         all_merges = self.benchmarks[case_key].result["merges"]
-        if recursive:
-            final_merges = {}
-            for merges in all_merges:
-                for merge in merges:
-                    for m in merge:
-                        new_list = m
-                        for k in m:
-                            if k in final_merges:
-                                new_list.remove(k)
-                                new_list += final_merges[k]
-                        final_merges[m[0]] = new_list
-            all_merges = list(final_merges.values())
+        # if recursive:
+        #     final_merges = {}
+        #     for merges in all_merges:
+        #         for merge in merges:
+        #             for m in merge:
+        #                 new_list = m
+        #                 for k in m:
+        #                     if k in final_merges:
+        #                         new_list.remove(k)
+        #                         new_list += final_merges[k]
+        #                 final_merges[m[0]] = new_list
+        #     all_merges = list(final_merges.values())
 
         from spikeinterface.widgets import plot_potential_merges
 
diff --git a/src/spikeinterface/curation/auto_merge.py b/src/spikeinterface/curation/auto_merge.py
index e686b7ae96..e2b219bdbe 100644
--- a/src/spikeinterface/curation/auto_merge.py
+++ b/src/spikeinterface/curation/auto_merge.py
@@ -446,7 +446,16 @@ def auto_merge_units_internal(
             merged_units = len(merge_unit_groups) > 0
 
         if extra_outputs:
-            merge_unit_groups = all_merging_groups
+            merge_unit_groups = {}
+            for merges in all_merging_groups:
+                for m in merges:
+                    new_list = m
+                    for k in m:
+                        if k in merge_unit_groups:
+                            new_list.remove(k)
+                            new_list += merge_unit_groups[k]
+                    merge_unit_groups[m[0]] = new_list
+            merge_unit_groups = list(merge_unit_groups.values())
             outs = all_outs
 
     if extra_outputs:
@@ -751,7 +760,19 @@ def auto_merge_units(
         if len(to_be_launched) == 1:
             all_merging_groups = all_merging_groups[0]
             all_outs = all_outs[0]
-        return sorting_analyzer, all_merging_groups, all_outs
+        
+        merge_unit_groups = {}
+        for merges in all_merging_groups:
+            for m in merges:
+                new_list = m
+                for k in m:
+                    if k in merge_unit_groups:
+                        new_list.remove(k)
+                        new_list += merge_unit_groups[k]
+                merge_unit_groups[m[0]] = new_list
+        merge_unit_groups = list(merge_unit_groups.values())
+
+        return sorting_analyzer, merge_unit_groups, all_outs
     else:
         return sorting_analyzer