Is it permissible to combine the intention of reading the twelfth part (juz') of the Qur'an for two different ختمة (complete recitations of the Qur'an), knowing that I previously lied about my recitation in these two ختمة?

Such an agreement on ختم القرآن (completing the recitation of the Qur'an) is hoped to be an act of cooperation in righteousness and piety, along with a reminder of the virtue of reciting the Qur'an, an encouragement for it, and the concealment of good deeds in pursuit of sincerity. Lying is not permissible; it is one of the major sins. Reporting that one has read when one has not is considered "المتشبع بما لم يعط" (claiming what one has not been given), as the Prophet, peace and blessings be upon him, said: "The one who claims what he has not been given is like one who wears two garments of falsehood." Therefore, you must repent for what has occurred from you. However, if what is required for recitation in both groups matches, and you recite it once, then it is permissible to inform the supervisors in both groups of that, and you will be rewarded for reciting it once.