According to your description, the IOU can be established.

According to the writing habits of China people, the last word of two repeated words is usually replaced by two points. This writing habit should be recognized by the court.

However, we should know that the handwritten signature must be applied for handwriting identification when the other party denies it, but handwriting identification may not be able to make an accurate judgment 100%, so it cannot be identified in practice and the identification result is wrong. Therefore, there is such a risk in your IOU.

Of course, after the IOU is denied, you can also prove the fact that there is a loan between you through other evidence, such as bank remittance records, receipts, witness testimony and so on.

Above, I hope I can help you.