# Unique Lead field / Merge / Warning

**URL:** <https://forum.mautic.org/t/unique-lead-field-merge-warning/5892>\
**Category:** General Discussion\
**Created:** [February 23, 2016, 4:59pm UTC](https://forum.mautic.org/t/unique-lead-field-merge-warning/5892 "2016-02-23T16:59:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![helmut](https://avatars.discourse-cdn.com/v4/letter/h/cab0a1/32.png) [@helmut](https://forum.mautic.org/u/helmut)\
**Post date:** [February 23, 2016, 4:59pm UTC](https://forum.mautic.org/t/unique-lead-field-merge-warning/5892/1 "2016-02-23T16:59:18Z")

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Hi,  
  
  
  
I want to add a unique customer number as lead field.  
  
This number is optional - but if it is set it is unique.  
  
Is this a problem according to the Warning in the lead field editor (unwanted merges/tracking etc.)  
  
Are the null Value leads are all merged together - or is my use case ok ?  
  
  
  
thanks,  
  
helmut

---

<div class="post-metadata">

**Author:** ![helmut](https://avatars.discourse-cdn.com/v4/letter/h/cab0a1/32.png) [@helmut](https://forum.mautic.org/u/helmut)\
**Post date:** [February 23, 2016, 4:59pm UTC](https://forum.mautic.org/t/unique-lead-field-merge-warning/5892/2 "2016-02-23T16:59:18Z")

</div>

Hi,

I want to add a unique customer number as lead field.  
This number is optional - but if it is set it is unique.  
Is this a problem according to the Warning in the lead field editor (unwanted merges/tracking etc.)  
Are the null Value leads are all merged together - or is my use case ok ?

thanks,  
helmut