diff --git a/api/src/routes/helpers/auth-helpers.test.ts b/api/src/routes/helpers/auth-helpers.test.ts
new file mode 100644
index 00000000000..a68f6f4d9c1
--- /dev/null
+++ b/api/src/routes/helpers/auth-helpers.test.ts
@@ -0,0 +1,55 @@
+import Fastify, { FastifyInstance } from 'fastify';
+
+import db from '../../db/prisma';
+import { createUserInput } from '../../utils/create-user';
+import { findOrCreateUser } from './auth-helpers';
+
+const captureException = jest.fn();
+
+async function setupServer() {
+  const fastify = Fastify();
+  await fastify.register(db);
+  // @ts-expect-error we're mocking the Sentry plugin
+  fastify.Sentry = { captureException };
+  return fastify;
+}
+
+describe('findOrCreateUser', () => {
+  let fastify: FastifyInstance;
+  const email = 'test@user.com';
+  beforeAll(async () => {
+    fastify = await setupServer();
+  });
+
+  afterEach(async () => {
+    await fastify.prisma.user.deleteMany({ where: { email } });
+    await fastify.close();
+    jest.clearAllMocks();
+  });
+
+  it('should send a message to Sentry if there are multiple users with the same email', async () => {
+    await fastify.prisma.user.create({ data: createUserInput(email) });
+    await fastify.prisma.user.create({ data: createUserInput(email) });
+
+    await findOrCreateUser(fastify, email);
+
+    expect(captureException).toHaveBeenCalledTimes(1);
+    expect(captureException).toHaveBeenCalledWith(
+      new Error('Multiple user records found for: test@user.com')
+    );
+  });
+
+  it('should NOT send a message if there is only one user with the email', async () => {
+    await fastify.prisma.user.create({ data: createUserInput(email) });
+
+    await findOrCreateUser(fastify, email);
+
+    expect(captureException).not.toHaveBeenCalled();
+  });
+
+  it('should NOT send a message if there are no users with the email', async () => {
+    await findOrCreateUser(fastify, email);
+
+    expect(captureException).not.toHaveBeenCalled();
+  });
+});
diff --git a/api/src/routes/helpers/auth-helpers.ts b/api/src/routes/helpers/auth-helpers.ts
index b82da1d28c8..762c0ece13c 100644
--- a/api/src/routes/helpers/auth-helpers.ts
+++ b/api/src/routes/helpers/auth-helpers.ts
@@ -10,15 +10,21 @@ import { createUserInput } from '../../utils/create-user';
 export const findOrCreateUser = async (
   fastify: FastifyInstance,
   email: string
-) => {
+): Promise<{ id: string }> => {
   // TODO: handle the case where there are multiple users with the same email.
   // e.g. use findMany and throw an error if more than one is found.
-  const existingUser = await fastify.prisma.user.findFirst({
+  const existingUser = await fastify.prisma.user.findMany({
     where: { email },
     select: { id: true }
   });
+  if (existingUser.length > 1) {
+    fastify.Sentry.captureException(
+      new Error(`Multiple user records found for: ${email}`)
+    );
+  }
+
   return (
-    existingUser ??
+    existingUser[0] ??
     (await fastify.prisma.user.create({
       data: createUserInput(email),
       select: { id: true }