Let's say that you are reviewing your MRR metrics and when looking at your Current MRR and Last Month MRR totals, you noticed that the "vs" Month-over-Month total does not match the Last Month MRR total:
In this example case posted above, this is expected behavior.
The reason why the Last Month MRR metric is not matching the "Vs" month-over-month metric under Current MRR is because the Last Month metric reflects the MRR on the last day of the previous month. In this example, March has 31 days and April has 30 and this is where the difference lies. The Vs Month over month total is using the March 30th MRR total whereas the Last Month MRR is displaying the March 31st MRR total.
You can confirm this by changing the MRR filter to Daily and see the MRR totals for March 30 and March 31 (or whichever two months you are comparing).
As you can see, the Last Month MRR and the vs month-over-month total can only be expected to match up when the current month and the previous month duration both total 30 days. If one month is 30 days and the other is 31 days, these calculations will mismatch.