Then just keep them two separate lines and do as I said, time each line to the times you want it to appear during. For example like this:
Code:
Dialogue: 0,0:01:20.00,0:01:27.00,Default,,0000,0000,0000,,This is the first line
Dialogue: 0,0:01:23.00,0:01:27.00,Default,,0000,0000,0000,,This is the second line
You can optionally give the second line a different styling to make it clear that it's different from the first.