Spline Mirror [BUG]

Create a Spline on a Level Make Some curved lines with some rotations
Then try to duplicate and mirror it… on some (+ALT) positions the rotations are BROKEN…
Mirroring was done with RMB → Transform on … (well i trying all combinantions so to be sure :-p )

can i mirror a spline with an other way? [this isnt a landscape spline]

1.You can se both splines LEFT IS THE ORIGINAL ]
2.How the LEFT spline is
3.How the DUPLICATED SPLINE (RIGHT) meshes up…