The same rules apply to any kind of line, including a wave.
Often, the caller will ask the dancers to turn again at the end, by adding something like "Face Right". This means turn 1/4 (90 degrees) after the Double Pass Thru. Sometimes the word "Face" will be omitted, and the caller will just say "Tag the Line Right".
In this case, the result will be a new line, with the four dancers standing as a group in the same four spots as the original line (but with the individual dancers in different spots and possibly facing different directions).