When you upload a new Project to Behance and it imports to your Adobe Portfolio, or when you upload a new Project directly to Adobe Portfolio - your Project will appear in all of your Galleries in Manage Content.
However, each Project appears this way as to offer you the choice to toggle them 'on' or 'off' in your Galleries based on how you would like to organize and display your work.
Click the sliding button next to the Project you'd like to appear in a Gallery to toggle it 'on' or 'off' in that Gallery.
*Please note, deleting a Project from a Gallery will remove it from all other Galleries as well. You will always want to toggle it off instead.