When two people need to sign at the same time, it is usually agreed that one of them should sign first and then leave the remaining space for the other person to sign. This is to ensure the order and clarity of signatures and avoid overlapping or confusion of signatures. By asking one person to sign first, and then leaving enough space for another person to sign, the readability and accuracy of the signature can be guaranteed. This practice is very common in contracts, documents or other occasions where both parties need to sign and confirm.