I presume you are referring to the staves, and that the new track displays a grand staff, rather than a sigle staff. I do not see any improper double barlines.
Those of us who use the Score Editor are still getting used to everything, and features are quite different than the old one
It would pay to spend time learning how it works, since it has no trace of anything from the legacy editor.
For example, the track you copied to is set to an instrument that would usually have a grand staff, so you can change the instrument type to one that does use a single staff.
Staff type:
