most memorial parks have restrictions for how many cadavers can be buried per lot. each lot can accommodate 2(one on top the other), each of those can't be opened/exhumed once sealed.
ex.; each 'vault' are allowed with 1 'fresh' cadaver(as they called it) + 1 bones or ashes. unlike with the public sementeryo that you can exhume tombs after 5 years then bury another one plus 'angkas'(bones or ashes) pa long as you owned the lot, hence you see multiple tombstones.