Hi,
This is because of the verge tiles. You should disable Left and Right verges from the Parameters rollout. Unfortunately though, the versions that are included with the plugin have a small issue caused by a change to recent versions of RailClone which stops these settings from working correctly.
To fix it, please find attached the reworked styles scene (rc_ridge_tiles.max / rc_concrete_tiles.max) - please use these to overwrite your local copy (by default located under C:\Users\<yourUsername>\AppData\Local\Itoo Software\RailClone Pro\lib\default1\Architecture\Exterior\Roofing\Hips and Ridges\objects / C:\Users\<yourUsername>\AppData\Local\Itoo Software\RailClone Pro\lib\default1\Architecture\Exterior\Roofing\Tiles\objects).
If there is anything else we can help with, please let us know.
Best regards,