You can apply for handwriting identification. However, the date of signing is inconsistent with the borrower's signature, which does not necessarily affect the validity of the loan, and needs to be analyzed according to the specific situation. The signatures of ordinary borrowers are true, and the main contents of IOUs (such as loan term, amount, interest, etc.) are also written by borrowers themselves. Even if the signature date below is different, it will not affect the validity of the IOU. However, if there are other circumstances, such as the repayment date is not written on the IOU, then the signing date is very important, which is the basis for determining the borrowing time and judging the limitation of action. So you need to judge whether it is necessary to do handwriting identification according to the above specific conditions.