One of our clients exchange accounts is behaving very strangely. When he creates a Calendar appointment everything looks fine, but after a few hours the appointment has cloned itself to multiple appointments. All same time, same day and so forth. Old already created/passed appointments are fine, but new and active appointments are being cloned. Here is a screenshot: Screenshot of the issue

Hi Any update on this thread? CheersZi Feng TechNet Community Support

Hello Sorry for the late reply No there are no 3rd party addins active. Neither are there any deligates. The inbox and the trash is empty. Ive never encountered this issue before