diff --git a/src/core/__tests__/ReactCompositeComponent-test.js b/src/core/__tests__/ReactCompositeComponent-test.js
index 4c2c8e3aad..76c8b2c2a8 100644
--- a/src/core/__tests__/ReactCompositeComponent-test.js
+++ b/src/core/__tests__/ReactCompositeComponent-test.js
@@ -500,50 +500,6 @@ describe('ReactCompositeComponent', function() {
     );
   });
 
-  it('should warn when owner is necessary', function() {
-
-    var Chooser = React.createClass({
-      render: function() {
-        return this.props.selection == 1 ? this.props.child1 : this.props.child2;
-      }
-    });
-
-    var CoolParent1 = React.createClass({
-      render: function() {
-        return <Chooser
-          selection={this.props.selection}
-          child1={<input value='foo' readOnly='true' />}
-          child2={this.props.child2} />;
-      }
-    });
-
-    var CoolParent2 = React.createClass({
-      render: function() {
-        return <CoolParent1
-          selection={this.props.selection}
-          child2={<input value='foo' readOnly='true' />} />;
-      }
-    });
-
-    var div = document.createElement('div');
-    React.render(<CoolParent2 selection={1} />, div);
-    expect(console.warn.argsForCall.length).toBe(0);
-    React.render(<CoolParent2 selection={2} />, div);
-    expect(console.warn.argsForCall.length).toBe(1);
-    React.render(<CoolParent2 selection={1} />, div);
-    React.render(<CoolParent2 selection={2} />, div);
-    expect(console.warn.argsForCall.length).toBe(1);
-
-    expect(console.warn.argsForCall[0][0]).toBe(
-      'Warning: <input /> is being rendered by both CoolParent1 and ' +
-      'CoolParent2 using the same key (null) in the same place. Currently, ' +
-      'this means that they don\'t preserve state. This behavior should be ' +
-      'very rare so we\'re considering deprecating it. Please contact the ' +
-      'React team and explain your use case so that we can take that into ' +
-      'consideration.'
-    );
-  });
-
   it('should pass context', function() {
     var childInstance = null;
     var grandchildInstance = null;
diff --git a/src/core/__tests__/ReactMultiChild-test.js b/src/core/__tests__/ReactMultiChild-test.js
index 80dd0f14a9..2d7e1dfe27 100644
--- a/src/core/__tests__/ReactMultiChild-test.js
+++ b/src/core/__tests__/ReactMultiChild-test.js
@@ -83,7 +83,7 @@ describe('ReactMultiChild', function() {
       expect(mockUnmount.mock.calls.length).toBe(1);
     });
 
-    it('should replace children with different owners', function() {
+    it('should NOT replace children with different owners', function() {
       var container = document.createElement('div');
 
       var mockMount = mocks.getMockFunction();
@@ -116,8 +116,8 @@ describe('ReactMultiChild', function() {
         container
       );
 
-      expect(mockMount.mock.calls.length).toBe(2);
-      expect(mockUnmount.mock.calls.length).toBe(1);
+      expect(mockMount.mock.calls.length).toBe(1);
+      expect(mockUnmount.mock.calls.length).toBe(0);
     });
 
     it('should replace children with different keys', function() {
diff --git a/src/core/shouldUpdateReactComponent.js b/src/core/shouldUpdateReactComponent.js
index 7892c86375..f80cdde268 100644
--- a/src/core/shouldUpdateReactComponent.js
+++ b/src/core/shouldUpdateReactComponent.js
@@ -12,8 +12,6 @@
 
 'use strict';
 
-var warning = require('warning');
-
 /**
  * Given a `prevElement` and `nextElement`, determines if the existing
  * instance should be updated as opposed to being destroyed or replaced by a new
@@ -32,66 +30,11 @@ function shouldUpdateReactComponent(prevElement, nextElement) {
     if (prevType === 'string' || prevType === 'number') {
       return (nextType === 'string' || nextType === 'number');
     } else {
-      if (nextType === 'object' &&
-          prevElement.type === nextElement.type &&
-          prevElement.key === nextElement.key) {
-        var ownersMatch = prevElement._owner === nextElement._owner;
-        if (__DEV__) {
-          if (!ownersMatch) {
-            var prevName = null;
-            var nextName = null;
-            var nextDisplayName = null;
-            if (prevElement._owner != null &&
-                prevElement._owner.getPublicInstance() != null &&
-                prevElement._owner.getPublicInstance().constructor != null) {
-              prevName =
-                prevElement._owner.getPublicInstance().constructor.displayName;
-            }
-            if (nextElement._owner != null &&
-                nextElement._owner.getPublicInstance() != null &&
-                nextElement._owner.getPublicInstance().constructor != null) {
-              nextName =
-                nextElement._owner.getPublicInstance().constructor.displayName;
-            }
-            if (nextElement.type != null &&
-                nextElement.type.displayName != null) {
-              nextDisplayName = nextElement.type.displayName;
-            }
-            if (nextElement.type != null && typeof nextElement.type === 'string') {
-              nextDisplayName = nextElement.type;
-            }
-            if (typeof nextElement.type !== 'string' ||
-                nextElement.type === 'input' ||
-                nextElement.type === 'textarea') {
-              if ((prevElement._owner != null &&
-                  prevElement._owner._isOwnerNecessary === false) ||
-                  (nextElement._owner != null &&
-                  nextElement._owner._isOwnerNecessary === false)) {
-                if (prevElement._owner != null) {
-                  prevElement._owner._isOwnerNecessary = true;
-                }
-                if (nextElement._owner != null) {
-                  nextElement._owner._isOwnerNecessary = true;
-                }
-                warning(
-                  false,
-                  '<%s /> is being rendered by both %s and %s using the same ' +
-                  'key (%s) in the same place. Currently, this means that ' +
-                  'they don\'t preserve state. This behavior should be very ' +
-                  'rare so we\'re considering deprecating it. Please contact ' +
-                  'the React team and explain your use case so that we can ' +
-                  'take that into consideration.',
-                  nextDisplayName || 'Unknown Component',
-                  prevName || '[Unknown]',
-                  nextName || '[Unknown]',
-                  prevElement.key
-                );
-              }
-            }
-          }
-        }
-        return ownersMatch;
-      }
+      return (
+        nextType === 'object' &&
+        prevElement.type === nextElement.type &&
+        prevElement.key === nextElement.key
+      );
     }
   }
   return false;