Hi Nico, the first message is a known issue. Widgets are exported as part of all the Solution / AddOn modules that use them. It's on the R&D roadmap to solve this. The message should not be blocking for builds as long as the widgets are identical duplications.
The second error suggests that your module has a consistency error due to incompatibilty with it's dependencies (i.e. Atlas_Core), something is changed wrt to your publishing side. This may be related if the widgets are not the same and they have to be updated, but it may also be something else. The recommendation here is to validate the usages of the module and see whether that's compatible.