What happens when a reservation starts in one month and ends in another?
It is important to understand you want a different answer depending on what task you are doing.
If you are just getting through your rental day you probably want to see all reservations, regardless of which month they were booked in. I want to know if a bike is coming back today, even if it was checked out last month. We call this your operational visibility and it is what you view from within BRM, for example in your Reservation List Panel. But in reality, this does mean we kind of show you the same reservation in 2 places. That reservation that started in January and ended in February would show up in a January view and your February view.
Now imagine a different job you do, like looking at your graphs or exporting your data for your accountant. Now you want to see each timeframe (each month) without duplicating reservations so that each month added up is the same total as if you were to add up the whole year. This requires a strict policy about which reservations to include in each timeframe, and not making those reservations 'show up' in 2 timeframes. The policy we use is the rental start date. We call this statistical visibility.
This is the main reason why you may see differences between your statistics (graphs and exports) and your operational numbers. (within BRM)
The diagram below helps to illustrate the issue.