diff --git a/packages/extension/src/testTree.ts b/packages/extension/src/testTree.ts
index 8a85b84d..42ba4b64 100644
--- a/packages/extension/src/testTree.ts
+++ b/packages/extension/src/testTree.ts
@@ -146,7 +146,11 @@ export class TestTree extends vscode.Disposable {
     const normalizedFile = normalize(file)
     const fileId = `${normalizedFile}${project}`
     const cached = this.fileItems.get(fileId)
-    if (cached) return cached
+    if (cached) {
+      // the file can be included in several configs (#799)
+      if (!cached.tags.includes(api.tag)) cached.tags = [...cached.tags, api.tag]
+      return cached
+    }
 
     const fileUri = vscode.Uri.file(resolve(file))
     const parentItem = this.getOrCreateFolderTestItem(api, dirname(file))
diff --git a/test/unit/testTree.test.ts b/test/unit/testTree.test.ts
new file mode 100644
index 00000000..e2a44ce1
--- /dev/null
+++ b/test/unit/testTree.test.ts
@@ -0,0 +1,44 @@
+import { resolve } from 'node:path'
+import * as vscode from 'vscode'
+import { expect } from 'chai'
+import type { VitestProcessAPI } from '../../packages/extension/src/apiProcess'
+import { TransformSchemaProvider } from '../../packages/extension/src/schemaProvider'
+import { TagsManager } from '../../packages/extension/src/tagsManager'
+import { TestTree } from '../../packages/extension/src/testTree'
+
+describe('TestTree', () => {
+  it('adds every config tag to a shared test file', () => {
+    const controller = vscode.tests.createTestController('test-tree', 'Vitest')
+    const loader = controller.createTestItem('loader', 'Loading')
+    const schemaProvider = new TransformSchemaProvider(async () => null)
+    const tree = new TestTree(controller, loader, new TagsManager(), schemaProvider)
+    const root = resolve(__dirname, '../..')
+    const workspaceFolder = {
+      uri: vscode.Uri.file(root),
+      name: 'vscode',
+      index: 0,
+    }
+    const file = resolve(__dirname, 'testTree.test.ts')
+    const metadata = { project: '', pool: 'threads' }
+    const baseApi = {
+      tag: new vscode.TestTag('root:vitest.config.base.ts'),
+    } as VitestProcessAPI
+    const packageApi = {
+      tag: new vscode.TestTag('foo:vitest.config.ts'),
+    } as VitestProcessAPI
+
+    tree.reset([workspaceFolder])
+    const item = tree.getOrCreateFileTestItem(baseApi, metadata, file)
+    const cachedItem = tree.getOrCreateFileTestItem(packageApi, metadata, file)
+
+    expect(cachedItem).to.equal(item)
+    expect(cachedItem.tags.map((tag) => tag.id)).to.deep.equal([
+      'root:vitest.config.base.ts',
+      'foo:vitest.config.ts',
+    ])
+
+    tree.dispose()
+    schemaProvider.dispose()
+    controller.dispose()
+  })
+})