Hello GameMaker02,
I created a test to demonstrate different aspects of how you could possibly be getting these errors.
1.) After unwrapping, if you select all of your uv’s and you relax them a bit this could possibly solve your issue. There is no telling from the image you posted if you have one or many uv’s hiding under others. This should help eliminate that issue.
2.) I created a test sphere in Maya and then automatically unwrapped it. You can assign another UV channel while using Automatic unwrapping.
These are the Maya Screenshots.
I had to actually cut up the original automatic unwrap just to get something close to the result you had. I know I am using Maya 2015 so I realize Autodesk may have changed the way it unwraps.
Then I imported this into UE4. I kept everything default except for I assigned the lightmap coordinate index to 1.
The cylinder imported with the above screenshots is on the far left. The one in the middle was automatically with no seams on the surface, just on the edges where the extrudes take place. The one on the far right is done with planar mapping and with increased lightmap resolution.
I believe what you are experiencing is a workflow issue. The overlapping UV’s could be a result of UV padding as outlined here.
Please look into these workflows and see if you are able to resolve the issue on the dome.
Thank you,