Suppose we have enabled (out of the box) data audit feature for a particular entity and then we are updating its record programmatically in the following manner (the way we usually do)
myEntityRecord.new_addressname = txtAddressName.Text;
myEntityRecord.new_street2 = txtStreet2.Text;
myEntityRecord.new_city = txtCity.Text;
myEntityRecord.new_state = txtState.Text;
myEntityRecord.new_zip = txtZipCode.Text;
Now what happens over here is that all of these fields will appear as “changed field” in Audit History even if we haven’t changed its value.
Here in the above screen shot we can see the same value for fields in old value and new value column. This is something we should be aware of while updating records programmatically in CRM.