The father-and-son duo alleged to have gunned down 15 people on Australia’s Bondi Beach holed themselves up in a Philippines hotel for weeks and left a tip on their way out, staff told AFP Thursday.Australian authorities are investigating whether Sajid Akram and his son Naveed trained with extremists last month during a trip to the southern Mindanao region where there is a long history of extremist insurgencies.For all the latest headlines follow our Google News channel online or via the app.The Philippines says there is no evidence to suggest that the country was being used to coach terrorists.The men entered the Philippines on November 1, with Davao listed as their final destination, immigration officials confirmed this week.They checked into room 315 of the GV Hotel the same day, paying 930 pesos (about $16) per night for the small room with two single beds.The men typically only left their room for an hour or so each day and largely kept to themselves, night desk manager Angelica