Overlapping UVs....

Hi, I have my objects mapped to an atlas texture, so when I made UV mapping, I shared the same texture space for many faces in the same object… for instance, in the attached picture, those uv are from a stair… each block using the same texture space… Then I have noticed on FBX importer (from Unreal) that there are overlapping uv in my mesh, so I´m wondering how good is to use atlas in Unreal projects, maybe it is better to use a single unwrapped and non overlapped uv texture for each objects?.. isn’t performance killer or it is just my imagination?

Another way I think could be a good idea, is to create a second UV for my meshes, which unwraps the object without overlapping… may be it works?..
What is the flow that fits better for Unreal ?