True Liberation

These are not at all contradictory. The statements of enlightened people are like device; to awaken. He said that he would (not) come again to those people who were new. This declaration by Osho was prior to 1970 that do not worry and continue your Sadhana. Even if I depart in between, I would return and (help) maintain the continuity of your Sadhana. This was said to encourage people so that they would start the journey.
The second statement was made to those people who would have fallen prey to lethargy and thought, “What is the hurry, we will take the journey in next life, Master would also be with us.”
Osho did not say, “No, this is my last birth. It is impossible to return! Nobody can come back after enlightenment.”
The first statement is a device; to accelerate the quest, to bring intensity and momentum in Sadhana. The second statement is also a device to maintain the momentum of Sadhana. I will tell you the third point that it is the freedom of an enlightened person to return if he wants to and not to return if he does not want to. What else is the meaning of a liberated person? There are no bondages. He is neither bound to come nor bound to return. It is his will, his choice.
Hence, there is no contradiction in the two statements. Both statements are a form of device. The enlightened persons are free. If they wish, they will come. Yet again do Leela. Once again, tour the planet Earth. If they do not wish then they would not come. They are free to do either thing. This is the very meaning of liberation. This is the meaning of Enlightenment.