diff --git a/packages/@aws-cdk/aws-codepipeline-actions/lib/codecommit/source-action.ts b/packages/@aws-cdk/aws-codepipeline-actions/lib/codecommit/source-action.ts
index caaa5ee3ed174..2fa7a67b29b93 100644
--- a/packages/@aws-cdk/aws-codepipeline-actions/lib/codecommit/source-action.ts
+++ b/packages/@aws-cdk/aws-codepipeline-actions/lib/codecommit/source-action.ts
@@ -87,7 +87,10 @@ export class CodeCommitSourceAction extends Action {
   private readonly props: CodeCommitSourceActionProps;
 
   constructor(props: CodeCommitSourceActionProps) {
-    const branch = props.branch || 'master';
+    const branch = props.branch ?? 'master';
+    if (!branch) {
+      throw new Error("'branch' parameter cannot be an empty string");
+    }
 
     super({
       ...props,
@@ -119,7 +122,8 @@ export class CodeCommitSourceAction extends Action {
     const createEvent = this.props.trigger === undefined ||
       this.props.trigger === CodeCommitTrigger.EVENTS;
     if (createEvent) {
-      this.props.repository.onCommit(stage.pipeline.node.uniqueId + 'EventRule', {
+      const branchIdDisambiguator = this.branch === 'master' ? '' : `-${this.branch}-`;
+      this.props.repository.onCommit(`${stage.pipeline.node.uniqueId}${branchIdDisambiguator}EventRule`, {
         target: new targets.CodePipeline(stage.pipeline),
         branches: [this.branch],
       });
diff --git a/packages/@aws-cdk/aws-codepipeline-actions/test/codecommit/test.codecommit-source-action.ts b/packages/@aws-cdk/aws-codepipeline-actions/test/codecommit/test.codecommit-source-action.ts
index 33f0d72bca24d..0650c50f2b596 100644
--- a/packages/@aws-cdk/aws-codepipeline-actions/test/codecommit/test.codecommit-source-action.ts
+++ b/packages/@aws-cdk/aws-codepipeline-actions/test/codecommit/test.codecommit-source-action.ts
@@ -110,6 +110,66 @@ export = {
       test.done();
     },
 
+    'cannot be created with an empty branch'(test: Test) {
+      const stack = new Stack();
+      const repo = new codecommit.Repository(stack, 'MyRepo', {
+        repositoryName: 'my-repo',
+      });
+
+      test.throws(() => {
+        new cpactions.CodeCommitSourceAction({
+          actionName: 'Source2',
+          repository: repo,
+          output: new codepipeline.Artifact(),
+          branch: '',
+        });
+      }, /'branch' parameter cannot be an empty string/);
+
+      test.done();
+    },
+
+    'allows using the same repository multiple times with different branches when trigger=EVENTS'(test: Test) {
+      const stack = new Stack();
+
+      const repo = new codecommit.Repository(stack, 'MyRepo', {
+        repositoryName: 'my-repo',
+      });
+      const sourceOutput1 = new codepipeline.Artifact();
+      const sourceOutput2 = new codepipeline.Artifact();
+      new codepipeline.Pipeline(stack, 'MyPipeline', {
+        stages: [
+          {
+            stageName: 'Source',
+            actions: [
+              new cpactions.CodeCommitSourceAction({
+                actionName: 'Source1',
+                repository: repo,
+                output: sourceOutput1,
+              }),
+              new cpactions.CodeCommitSourceAction({
+                actionName: 'Source2',
+                repository: repo,
+                output: sourceOutput2,
+                branch: 'develop',
+              }),
+            ],
+          },
+          {
+            stageName: 'Build',
+            actions: [
+              new cpactions.CodeBuildAction({
+                actionName: 'Build',
+                project: new codebuild.PipelineProject(stack, 'MyProject'),
+                input: sourceOutput1,
+              }),
+            ],
+          },
+        ],
+      });
+
+      test.done();
+    },
+
     'exposes variables for other actions to consume'(test: Test) {
       const stack = new Stack();