Ive noticed that yesterday I had 4 data usages of 5.00 MB. All at the exact same time ! Why would that appear like that ? I don't remember doing anything like that once let alone 4 times. This sort of thing has happened but then it's a large amount (eg. 52.3 mb)
In addition to Robert's suggestion, if you are on a fast data connection (LTE) it is possible to have more that one measure of packets occur in the same minute. Was there any other data used in previous or subsequent minutes?