There’s a bug in Rental Hive - when a user is signed out and places a booking that starts and ends on the same day, is then redirected to sign in, after sign in the cart displays the price as x2 days instead of x1 day price.
When you rebook it now that you are signed in, the correct price displays (1 day).
The issue probably occurs because of the double redirect, since the booked product is added to cart on redirect. We added this issue to the bug tracker and will fix it in the next Bookings update, thanks!