Can Wholesalers accept the keys prior to the closing?

[Lukas Vanagaitis]

There is a clause in Purchase and Sale Agreement stating that seller allows 24-hour access to the property and provides 1 set of keys in order to perform proper due diligence until the sale is completed. 

Does that make sense and is it legal? Can Wholesalers accept keys of a vacant property from the Seller after the Contract is signed and enter the property with potential Investors?

Thanks