Based on my understanding, the tracking code value in the report will depend on the allocation which you have set for that variable. If you set the allocation as 'Most Recent' then the tracking code value will be 'socialnetwork' but if the allocation is set to 'Original Value' then it will be 'banner'. You check the allocation of the eVar using the below steps:
1. Go to Analytics > Admin.
2. Select the report suite & click on the 'Edit Settings' > Conversion > Conversion Variables.