Yes - as long as the bookings are for the same venue.
When you are checking out, you may get the option to Add to Basket or Checkout. To continue browsing and add other campaigns, click Add to Basket.
This will add the booking to your Basket and you can continue to browse on the marketplace.
Alternatively, you can click to add it to your basket, and then select continue browsing to get back to the marketplace.
Note;
If you are booking for separate venues, the bookings would need to be put through separately. Complete check-out for one venue, and then go back to the Book menu.