diff --git a/lib/media/drm_engine.js b/lib/media/drm_engine.js
index 200011c088..f1de943ba1 100644
--- a/lib/media/drm_engine.js
+++ b/lib/media/drm_engine.js
@@ -1825,9 +1825,16 @@ shaka.media.DrmEngine = class {
         // audio adaptations, so we shouldn't have to worry about checking
         // robustness.
         if (drm1.keySystem == drm2.keySystem) {
+          /** @type {Array<shaka.extern.InitDataOverride>} */
           let initData = [];
           initData = initData.concat(drm1.initData || []);
           initData = initData.concat(drm2.initData || []);
+          initData = initData.filter((d, i) => {
+            return d.keyId === undefined || i === initData.findIndex((d2) => {
+              return d2.keyId === d.keyId;
+            });
+          });
+
           const keyIds = drm1.keyIds && drm2.keyIds ?
               new Set([...drm1.keyIds, ...drm2.keyIds]) :
               drm1.keyIds || drm2.keyIds;
diff --git a/test/media/drm_engine_unit.js b/test/media/drm_engine_unit.js
index 4cb204d9cb..c6208b651d 100644
--- a/test/media/drm_engine_unit.js
+++ b/test/media/drm_engine_unit.js
@@ -2152,6 +2152,50 @@ describe('DrmEngine', () => {
           [drmInfoAudio]);
       expect(returned).toEqual([drmInfoDesired]);
     });
+
+    it('dedupes the merged init data based on keyId matching', () => {
+      const serverCert = new Uint8Array(0);
+      const drmInfoVideo = {
+        keySystem: 'drm.abc',
+        licenseServerUri: 'http://abc.drm/license',
+        distinctiveIdentifierRequired: false,
+        persistentStateRequired: true,
+        videoRobustness: 'really_really_ridiculously_good',
+        serverCertificate: serverCert,
+        serverCertificateUri: '',
+        initData: [{keyId: 'v-init'}],
+        keyIds: new Set(['deadbeefdeadbeefdeadbeefdeadbeef']),
+      };
+      const drmInfoAudio = {
+        keySystem: 'drm.abc',
+        licenseServerUri: undefined,
+        distinctiveIdentifierRequired: true,
+        persistentStateRequired: false,
+        audioRobustness: 'good',
+        serverCertificate: undefined,
+        serverCertificateUri: '',
+        initData: [{keyId: 'v-init'}, {keyId: 'a-init'}],
+        keyIds: new Set(['eadbeefdeadbeefdeadbeefdeadbeefd']),
+      };
+      const drmInfoDesired = {
+        keySystem: 'drm.abc',
+        licenseServerUri: 'http://abc.drm/license',
+        distinctiveIdentifierRequired: true,
+        persistentStateRequired: true,
+        audioRobustness: 'good',
+        videoRobustness: 'really_really_ridiculously_good',
+        serverCertificate: serverCert,
+        serverCertificateUri: '',
+        initData: [{keyId: 'v-init'}, {keyId: 'a-init'}],
+        keyIds: new Set([
+          'deadbeefdeadbeefdeadbeefdeadbeef',
+          'eadbeefdeadbeefdeadbeefdeadbeefd',
+        ]),
+      };
+      const returned = shaka.media.DrmEngine.getCommonDrmInfos([drmInfoVideo],
+          [drmInfoAudio]);
+      expect(returned).toEqual([drmInfoDesired]);
+    });
   }); // describe('getCommonDrmInfos')
 
   describe('configure', () => {