Gmail for Android creates duplicate Exchange contacts

We identified a reproducible issue affecting all users in our organization when using Gmail for Android with Exchange ActiveSync.

Environment

• Gmail client: Android-Mail/2026.09.14.986636867.Release
• Android Enterprise
• Motorola Edge 50 Neo
• Motorola G71
• Exchange Server Subscription Edition (latest updates)
• Ivanti EPMM 12.7.0.0
• Ivanti Sentry 10.7.3

Issue After device reboot or disable work profile:

1. Existing Exchange contacts remain on device.
2. Gmail starts a new ActiveSync contact synchronization.
3. Another complete copy of the same contacts is created.
4. Contact count continuously grows.

Example:

Initial sync: ~450 contacts

After reboot #1: ~900 contacts

After reboot #2: ~1350 contacts

After reboot #3: ~1800 contacts
 

Investigation results

• Outlook and Exchange mailbox do not contain duplicate contacts.
• Duplicates exist only on Android devices.
• Email and Calendar synchronization work correctly.
• Same DeviceId is used before and after reboot.
• Exchange returns HTTP 200 and successful ActiveSync responses.
• Exchange does not return ActiveSync errors or invalid SyncKey responses.

Mailbox logs show that after reboot the Gmail client starts a new synchronization from:

<SyncKey>0</SyncKey>

for contact collections.

Exchange then correctly returns the contact set using:

<Commands>

<Add>

...

</Add>

</Commands>

which results in another copy of the existing contacts being stored locally.

We have been using Gmail for Android with Exchange ActiveSync and certificate-based authentication for many years without any issues. This configuration is required in our environment because users authenticate to Exchange through certificates and Ivanti Sentry. The solution worked correctly for a long time, but during the last few months we started experiencing contact duplication issues. Unfortunately, we do not know the exact date when the problem first appeared.