# How can I keep both values of a field after the merge

## How to Keep Track of Candidate Record Values During a Merge

When merging duplicate records in Salesforce using Delpha, the **Master record is retained** while the **Candidate record is deleted**. Standard merge logic retains only selected field values based on your Merge Field Rules.

However, in some cases, you may want to **retain and track values from the Candidate record** — such as legacy IDs, previous emails, or alternate names — for audit, traceability, or post-merge processing.

Delpha allows this via the **“Concatenate and Unicity” operation**.

## Step-by-Step: Set Up a Merge Rule to Preserve Candidate Values

1. Open the **Delpha Setup** app.
2. Go to the **Duplicate Settings** tab.
3. Select the target **object** (e.g., Account, Contact).
4. Scroll to the **Merge Field Rules** section.
5. Click **New Rule**.

Then configure the following:

| Field            | Description                                                                                |
| ---------------- | ------------------------------------------------------------------------------------------ |
| **Action**       | Select `Operation`                                                                         |
| **Input Field**  | Choose the field whose values (from both records) you want to track (e.g., `Legacy_Id__c`) |
| **Output Field** | A custom field (usually text or long text) where the unique values will be stored          |
| **Operation**    | Select `Concatenate and Unicity`                                                           |

This operation:

* Collects values from **both the Master and Candidate**
* **Deduplicates them**
* Combines them into the **Output Field**

## Use Case: Tracking Legacy IDs

If you store legacy system IDs in a custom field (e.g., `Legacy_Id__c`), you can use this rule to **keep all IDs** from merged records:

This ensures historical traceability and can be used in **post-merge automation or reporting**.

<table data-header-hidden><thead><tr><th valign="top"></th><th valign="top"></th><th valign="top"></th></tr></thead><tbody><tr><td valign="top"><p><strong>Master</strong><br>Legacy Id: <mark style="color:green;">FJQn</mark></p><p>Merged Legacy Ids : &#x3C;Empty></p></td><td valign="top"><p><strong>Candidate</strong></p><p>Legacy Id: <mark style="color:red;">rAAH</mark></p><p>Merged Legacy Ids: <mark style="color:orange;">oYAAX</mark></p></td><td valign="top"><p><strong>Master and Not Empty + Concatenate and Unicity</strong></p><p>Legacy Id: <mark style="color:green;">FJQn</mark></p><p>Merged Legacy Ids: <mark style="color:orange;">oYAAX</mark>, <mark style="color:red;">rAAH</mark></p></td></tr></tbody></table>

## Result

After merging:

* The **Output Field** contains all unique values from both records
* You preserve key information from deleted candidates
* Your data governance and traceability stay intact


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