diff --git a/packages/data/CHANGELOG.md b/packages/data/CHANGELOG.md
index 60592bd2ee53f..f422a9824cd74 100644
--- a/packages/data/CHANGELOG.md
+++ b/packages/data/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Breaking Changes
+
+-   The `registry.register` function will no longer register a store if another instance is registered with the same name.
+
 ## 8.6.0 (2023-03-15)
 
 ## 8.5.0 (2023-03-01)
diff --git a/packages/data/src/registry.js b/packages/data/src/registry.js
index 8fe418e5d8bfa..7a913da488f46 100644
--- a/packages/data/src/registry.js
+++ b/packages/data/src/registry.js
@@ -211,10 +211,18 @@ export function createRegistry( storeConfigs = {}, parent = null ) {
 	/**
 	 * Registers a store instance.
 	 *
-	 * @param {string} name  Store registry name.
-	 * @param {Object} store Store instance object (getSelectors, getActions, subscribe).
+	 * @param {string}   name        Store registry name.
+	 * @param {Function} createStore Function that creates a store object (getSelectors, getActions, subscribe).
 	 */
-	function registerStoreInstance( name, store ) {
+	function registerStoreInstance( name, createStore ) {
+		if ( stores[ name ] ) {
+			// eslint-disable-next-line no-console
+			console.error( 'Store "' + name + '" is already registered.' );
+			return stores[ name ];
+		}
+
+		const store = createStore();
+
 		if ( typeof store.getSelectors !== 'function' ) {
 			throw new TypeError( 'store.getSelectors must be a function' );
 		}
@@ -262,6 +270,8 @@ export function createRegistry( storeConfigs = {}, parent = null ) {
 				// ignore it.
 			}
 		}
+
+		return store;
 	}
 
 	/**
@@ -270,7 +280,9 @@ export function createRegistry( storeConfigs = {}, parent = null ) {
 	 * @param {StoreDescriptor} store Store descriptor.
 	 */
 	function register( store ) {
-		registerStoreInstance( store.name, store.instantiate( registry ) );
+		registerStoreInstance( store.name, () =>
+			store.instantiate( registry )
+		);
 	}
 
 	function registerGenericStore( name, store ) {
@@ -278,7 +290,7 @@ export function createRegistry( storeConfigs = {}, parent = null ) {
 			since: '5.9',
 			alternative: 'wp.data.register( storeDescriptor )',
 		} );
-		registerStoreInstance( name, store );
+		registerStoreInstance( name, () => store );
 	}
 
 	/**
@@ -294,10 +306,10 @@ export function createRegistry( storeConfigs = {}, parent = null ) {
 			throw new TypeError( 'Must specify store reducer' );
 		}
 
-		const store = createReduxStore( storeName, options ).instantiate(
-			registry
+		const store = registerStoreInstance( storeName, () =>
+			createReduxStore( storeName, options ).instantiate( registry )
 		);
-		registerStoreInstance( storeName, store );
+
 		return store.store;
 	}
 
diff --git a/packages/data/src/test/registry.js b/packages/data/src/test/registry.js
index 1422ef1082556..b9288eae821d8 100644
--- a/packages/data/src/test/registry.js
+++ b/packages/data/src/test/registry.js
@@ -481,41 +481,50 @@ describe( 'createRegistry', () => {
 	} );
 
 	describe( 'register', () => {
+		const store = createReduxStore( 'demo', {
+			reducer( state = 'OK', action ) {
+				if ( action.type === 'UPDATE' ) {
+					return 'UPDATED';
+				}
+				return state;
+			},
+			actions: {
+				update: () => ( { type: 'UPDATE' } ),
+			},
+			selectors: {
+				getValue: ( state ) => state,
+			},
+		} );
+
 		it( 'should work with the store descriptor as param for select', () => {
-			const store = createReduxStore( 'demo', {
-				reducer: ( state = 'OK' ) => state,
-				selectors: {
-					getValue: ( state ) => state,
-				},
-			} );
 			registry.register( store );
 
 			expect( registry.select( store ).getValue() ).toBe( 'OK' );
 		} );
 
 		it( 'should work with the store descriptor as param for dispatch', async () => {
-			const store = createReduxStore( 'demo', {
-				reducer( state = 'OK', action ) {
-					if ( action.type === 'UPDATE' ) {
-						return 'UPDATED';
-					}
-					return state;
-				},
-				actions: {
-					update() {
-						return { type: 'UPDATE' };
-					},
-				},
-				selectors: {
-					getValue: ( state ) => state,
-				},
-			} );
 			registry.register( store );
 
 			expect( registry.select( store ).getValue() ).toBe( 'OK' );
 			await registry.dispatch( store ).update();
 			expect( registry.select( store ).getValue() ).toBe( 'UPDATED' );
 		} );
+
+		it( 'should keep the existing store instance on duplicate registration', async () => {
+			registry.register( store );
+
+			await registry.dispatch( store ).update();
+			expect( registry.select( store ).getValue() ).toBe( 'UPDATED' );
+
+			registry.register( store );
+
+			// check that the state hasn't been reset back to `OK`, as a re-registration would do
+			expect( registry.select( store ).getValue() ).toBe( 'UPDATED' );
+
+			expect( console ).toHaveErroredWith(
+				'Store "demo" is already registered.'
+			);
+		} );
 	} );
 
 	describe( 'select', () => {