Parallel Or Double Sun Line
Two vertical lines on Mount of Sun means double Sun Line.
Mostly you will find double sun line on above heart line than below heart line.
As you know sun line can starts from any line or from any mount but mostly you will find sun line above heart line underneath ring finger.
Both lines should be strong and equal because if one line is weak then it should be considered as supportive line or influence line instead of Sun Line.
If sun line is crossed by influence line or there is a cross on sun line then it reduces the benefit of sun line. Triangle and square on sun line increases the benefit of sun line.