We have a solution based on Helix principles and we have separated TDS projects per Feature. For instance like this:
It cause duplication of the following items:
Here is the Habitat solution with TDS which has also this issue.
Is there any way to prevent this duplication like with Unicorn?
TDS always serializes data from the root item, there are no settings that allow you to only serialise a part of a tree. Logically speaking, this makes a lot of sense for a Helix based solution where each project is self contained, independent and does not have any knowledge of other TDS projects in the solution. This means each feature is deployable in it's own right.
What you should do however is to set Deployment Properties of the parent items to match your needs, either directly on the item or using the Deployment Property Manager which allows you to view and update deployment properties on many items at one time.
Most likely you will want to ensure you have set Deploy Once and No Child Synchronization on the /Sitecore/Templates/Feature items and set Always Update and Keep All Children Synchronized on the individual Feature folders.
