You have created Extension Fields in a particular screen which was automatically adapted to the migration template but it is displaying more than once in the latest template.
The cause for the issue is that you might be having more than one active solutions (add-on, PDI or service center delivered) in your system which has the same Extension Fields.
If the Extension Field is showing twice then it cause could be,
One of the solution is a patch solution. In the system where a customer-specific solution is developed, it is always the case that the fields of the productive solution and the patch solution are visible in parallel (after applying the solution in the system this is of course not the case).
As both solutions are active, the fields from both solutions are available in the migration template. This is a normal behavior and works as designed.
In order to be able to differentiate between these fields with same label, you can unhide line 4 and 5 of the source data sheets of the migration template in Microsoft Excel. These lines contain the technical names of the fields, starting with the prefix (namespace) of the respective solution. And this namespace in combination with the field label (which is also displayed in the excel sheet as column header) allows for identifying the correct fields.
We cannot disable or delete the old field since it will have persistency. We will not face this problem in production.
Q & A
There are two extension fields with same label but created through two different Add-Ons. One of the Add-on is disabled and the other one is still Active but in the migration template both the fields are active. Or the other field is from the Patch of the original solution and the patch is disabled.
>> Eventhough the Patch solution is disabled in the system, the extension fields package is still active due to which the fields are shown for the patch eventhough it is disabled. From extensibility perspective, this is the current behavior of the extensibility. Thus patch disabling would not affect the fields here and thus the fields are displayed twice.
Is this same behavior for the fields in Web Service.
>> Yes. but in Web Service there is a workaround that user can remove the fields from the original solution in the WSDL and perform the operation.
With respect to extensibility behavior is correct.
1. When a Solution is switched off, we do not delete the field. This is because, it can happen that at some point in time the same solution can be enabled again, so we need the extension fields and its data intact.
2. So from extensibility point of view the field behaves exactly as it is existing in the system and enabled (PDI solution lifecycle and extension field life cycle different).
3. If the field is added to a migration template and then the corresponding solution is switched off because the reason mentioned in point 1 and 2, we will not remove the field from the service. The migration template would be using the service directly. The reason for this is, it is not that straight forward from the migration also to do this as they also have other technical things ( example what if the user has downloaded a migration template locally and using it, one of the reason might be).
4. So all in all the behavior is expected, that even if the PDI solution is disabled the fields will remain as it is on the appearances.
As a workaround, user can hide/ignore the field which is irrelevant
KBA , SRD-CC , Cross Components , How To