Double time signatures when rejoining time signature changing bars in a part
1) As in screen shot 01, there is a time signature change in adjacent bars in a part.
2) Add a line break right at the change place. A time signature appears at the end of the first line, another appears at the beginning of the second line. That's normal.
3) Remove the line break. Now the two lines join again. However, double time signatures appear at the changing bar.
4) The first time signature cannot be deleted. Only the second can.