What's the significance of the double # in ##,#?

[adamdport]

In the docs https://github.com/telerik/kendo-intl/blob/master/docs/num-formatting/index.md you can see the example of the comma operator

The "," specifier—A group separator placeholder. It inserts a localized group separator between each group.

import { formatNumber } from '@telerik/kendo-intl';
formatNumber(12345678, "##,#"); // 12,345,678

What's the difference between ##,# and #,#? I played with it in stackblitz and can't seem to find any difference. Could your reply be added to that doc for the next guy? Thanks.