Hello Anon,
You could think of them as three variants, which reflect the three "types" of conditional statement:
A: A lie is always bad. After having told one lie, you will often have to tell another in order to be consistent. And in the end, things will be worse than [they would have been] if you had told the truth.
B: A lie is always bad. After having told one lie, you will often have to tell another in order to be consistent. And in the end, things will be worse than [they would be] if you told the truth.
C: A lie is always bad. After having told one lie, you will often have to tell another in order to be consistent. And in the end, things will be worse than [they are] if you tell the truth.
Best wishes,
MrP