diff --git a/services/audiopolicy/service/AudioPolicyService.cpp b/services/audiopolicy/service/AudioPolicyService.cpp
index fd10353..50a536b 100644
--- a/services/audiopolicy/service/AudioPolicyService.cpp
+++ b/services/audiopolicy/service/AudioPolicyService.cpp
@@ -516,7 +516,8 @@
 
 void AudioPolicyService::doOnCheckSpatializer()
 {
-    ALOGI("%s mSpatializer %p level %d", __func__, mSpatializer.get(), (int)mSpatializer->getLevel());
+    ALOGV("%s mSpatializer %p level %d",
+        __func__, mSpatializer.get(), (int)mSpatializer->getLevel());
 
     if (mSpatializer != nullptr) {
         // Note: mSpatializer != nullptr =>  mAudioPolicyManager != nullptr
diff --git a/services/audiopolicy/service/Spatializer.cpp b/services/audiopolicy/service/Spatializer.cpp
index 3860bbd..c376e57 100644
--- a/services/audiopolicy/service/Spatializer.cpp
+++ b/services/audiopolicy/service/Spatializer.cpp
@@ -373,6 +373,17 @@
         return BAD_VALUE;
     }
 
+    if (mSpatializerCallback != nullptr) {
+        if (IInterface::asBinder(callback) == IInterface::asBinder(mSpatializerCallback)) {
+            ALOGW("%s: Registering callback %p again",
+                __func__, mSpatializerCallback.get());
+            return NO_ERROR;
+        }
+        ALOGE("%s: Already one client registered with callback %p",
+            __func__, mSpatializerCallback.get());
+        return INVALID_OPERATION;
+    }
+
     sp<IBinder> binder = IInterface::asBinder(callback);
     status_t status = binder->linkToDeath(this);
     if (status == NO_ERROR) {