Promoting Infopath form fields to SharePoint - with out duplication

Scenario:
SharePoint 2010 form library is created using object model or schema definition in Visual Studio 2010 and form is created in InfoPath 2010 using InfoPath designer, When the fields are promoted to SharePoint Form library from InfoPath form it duplicates the filed in Form Library.


Solution:
When you promote a field from infopath form to sharepoint it creates a new field in form library with the name of promoted field, even if the field with that name exist it  creates a new field and give it different internal name.

Solution is when you are promoting a field from infopath form , select that field modify it select the SiteColumn group and SiteColumn from dropdowns as shown in figure belw....


For Example: if you have created a column which exist in DSL Columns group select DSL Columns from drop down.

now select the name of field from Site Column and click ok

Do same steps for all promoted fields...if you have already created those fields in FormLibrary...

Check the Image below with screenshot highlighting points above ...