InfoPath dropdown comes with an ability to have different values being sent to the list/database and a different value to be viewed by users. For eg., you bind a dropdown which fetches users from a SharePoint security group and you want to display the “Display Name” attribute of the user within the dropdown values at the same time you want to map this field to a People picker field within the list and for that purpose you want to send the “Login Name” attribute to the people picker field. In such a scenario, follow the screenshots to create a similar functionality.
Click on the Dropdown properties
Select the datasource from the Data source dropdown or you can create one here as well. Then click on the Select XPath button (highlighted in the image).
In the Entries field, select the parent node and click OK.
This will enable you to select two different values for the Value and the Display Name field.
Now from the returning values, select the ones you want for each field and save your form.
To view your changes, you may want to publish the form and verify the changes.