diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
index 134b7b4..ee08ccb 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
@@ -758,7 +758,8 @@
         } catch (DuplicateExecGroupError e) {
           throw new IllegalArgumentException(
               String.format(
-                  "An execution group named '%s' is inherited multiple times in %s ruleclass",
+                  "An execution group named '%s' is inherited multiple times with different"
+                      + " requirements in %s ruleclass",
                   e.getDuplicateGroup(), name));
         }
 
@@ -1419,14 +1420,22 @@
     }
 
     /**
-     * Adds execution groups to this rule class. Errors out if multiple groups with the same name
-     * are added.
+     * Adds execution groups to this rule class. Errors out if multiple different groups with the
+     * same name are added.
      */
     public Builder addExecGroups(Map<String, ExecGroup> execGroups) throws DuplicateExecGroupError {
       for (Map.Entry<String, ExecGroup> group : execGroups.entrySet()) {
         String name = group.getKey();
-        if (this.execGroups.put(name, group.getValue()) != null) {
-          throw new DuplicateExecGroupError(name);
+        if (this.execGroups.containsKey(name)) {
+          // If trying to add a new execution group with the same name as a execution group that
+          // already exists, check if they are equivalent and error out if not.
+          ExecGroup existingGroup = this.execGroups.get(name);
+          ExecGroup newGroup = group.getValue();
+          if (!existingGroup.equals(newGroup)) {
+            throw new DuplicateExecGroupError(name);
+          }
+        } else {
+          this.execGroups.put(name, group.getValue());
         }
       }
       return this;
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RuleClassBuilderTest.java b/src/test/java/com/google/devtools/build/lib/packages/RuleClassBuilderTest.java
index faa0cc2..ad4c470 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RuleClassBuilderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RuleClassBuilderTest.java
@@ -215,13 +215,38 @@
   }
 
   @Test
-  public void testDuplicateExecGroupNamesErrors() throws Exception {
+  public void testDuplicateExecGroupsThatAreEqualIsOk() throws Exception {
+    ExecGroup execGroup =
+        ExecGroup.create(
+            ImmutableSet.of(Label.parseAbsoluteUnchecked("//some/toolchain")),
+            ImmutableSet.of(Label.parseAbsoluteUnchecked("//some/constraint")));
+    RuleClass a =
+        new RuleClass.Builder("ruleA", RuleClassType.NORMAL, false)
+            .factory(DUMMY_CONFIGURED_TARGET_FACTORY)
+            .addExecGroups(ImmutableMap.of("blueberry", execGroup))
+            .add(attr("tags", STRING_LIST))
+            .build();
+    RuleClass b =
+        new RuleClass.Builder("ruleB", RuleClassType.NORMAL, false)
+            .factory(DUMMY_CONFIGURED_TARGET_FACTORY)
+            .addExecGroups(ImmutableMap.of("blueberry", execGroup))
+            .add(attr("tags", STRING_LIST))
+            .build();
+    RuleClass c = new RuleClass.Builder("$ruleC", RuleClassType.ABSTRACT, false, a, b).build();
+    assertThat(c.getExecGroups()).containsExactly("blueberry", execGroup);
+  }
+
+  @Test
+  public void testDuplicateExecGroupsThrowsError() throws Exception {
     RuleClass a =
         new RuleClass.Builder("ruleA", RuleClassType.NORMAL, false)
             .factory(DUMMY_CONFIGURED_TARGET_FACTORY)
             .addExecGroups(
                 ImmutableMap.of(
-                    "blueberry", ExecGroup.create(ImmutableSet.of(), ImmutableSet.of())))
+                    "blueberry",
+                    ExecGroup.create(
+                        ImmutableSet.of(Label.parseAbsoluteUnchecked("//some/toolchain")),
+                        ImmutableSet.of())))
             .add(attr("tags", STRING_LIST))
             .build();
     RuleClass b =
@@ -239,7 +264,8 @@
     assertThat(e)
         .hasMessageThat()
         .isEqualTo(
-            "An execution group named 'blueberry' is inherited multiple times in ruleC ruleclass");
+            "An execution group named 'blueberry' is inherited multiple times with different"
+                + " requirements in ruleC ruleclass");
   }
 
   @Test