If we send an SMS message to a DE that has duplicate entries for the same subscriber, will they receive multiple SMS, or does MobileConnect deduplicate sends based on the contact key?

We haven't seen an option to deduplicate subscribers like Email sends has.

2 Answers 2


It appears that MobileConnect automatically deduplicates based on the mobile number.


This actually goes a notch deeper. In MobileConnect your Contacts have a priority on them, which means you can never have two (or more) Contacts with priority 1 status.

By default a new entry with an existing Contacts mobile number will be set as priority 1 Contact and everyone else sharing this number (as their primary number) will be set as priority 2.

This means any personalization strings or lookups based on ContactKey or Mobile_Number you do in your SMS are based on the Contact having priority 1 status.

So while it's correct MobileConnect 'deduplicates' for an SMS send, it's actually based on the priority level - not the mobile number itself.

  • Thanks, I guess I've learnt a new SE trick today; If no one answers for a month, answer your own question and get downvoted and corrected in the process.
    – Luke BDD
    Sep 20, 2018 at 7:34

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