A visit is reported in each time period in which activity occurred. For example, suppose that a visit begins at 11:45 p.m. on Dec 1st, and continues until 12:30 a.m. on December 2nd. The visit is counted on December 1st and December 2. This reporting applies to other time periods, including weekly, monthly, quarterly, and yearly.Hence when you look for Page visits for a page by day , it will be shown for both the dates i.e. December 1 and Dec 2. However for Page visits by month it will only be counted once .For more details please see the link - https://marketing.adobe.com/resources/help/en_US/reference/metrics_visit.html.