What is the ruling of Islamic law regarding the issue of differing fatwas between two shaykhs, where one validates a contract and the other deems it necessary to renew it, and is following dispensations in this case considered a transgression?

Following concessions (rukhs) is forbidden if motivated by caprice and desire. However, if there is a genuine need for it, then there is no harm in it. The person afflicted with obsessive doubts (waswasa) is permitted to adopt the easier opinion to alleviate hardship. It is permissible for the ignorant person to follow (taqlid), and to adopt a concession from the sayings of scholars when there is a pressing need, without excessively seeking out concessions. Indeed, اختلاف (differences of opinion) are a mercy, as concessions are a mercy. There is no harm for the man in acting upon the opinion that the contract is valid, and he is not required to renew it. He should, moreover, ignore these obsessive doubts.