Is it correct to say that, when there is disagreement, one of the opinions must be correct and the other false, as Sheikh Al-Albani maintained?

This issue is one of the disputed matters among the Usuliyyun (jurists specializing in the principles of Islamic jurisprudence). The majority of them hold that the truth is one and does not multiply. This is the view of Abu Hanifa, Malik, Al-Shafi'i, and most jurists, and that the truth lies in one of the sayings, even if it is not apparent to us, yet it is definitively known to Allah. This opinion is the one relied upon. Al-Shawkani emphasizes that the Companions used to correct each other, which indicates that the truth does not multiply.

Nevertheless, the disagreement among mujtahids (independent jurists) in their pursuit of truth is permissible. The one who is correct receives two rewards, and the one who errs receives one reward, as stated in the noble Hadith. Sheikh Al-Albani encourages referring to the sayings of the mujtahids and benefiting from them in understanding the truth, especially if there is no explicit text in the Qur'an and Sunnah.

There is no sin upon the erring mujtahid who exerted their utmost effort to reach the truth; rather, they receive a reward. Similarly, for the muqallid (follower of a jurist), if their taqlid (following) is sound and not due to caprice or seeking concessions, then their taqlid is akin to following probabilistic evidence.