Hi. I would like to ask. If im going to aussie in march 2019 for a week, then back to kl. Then going to aussie for another trip in april 2019. How many times do i need to apply for visa?

Apply first visa for march 2019 trip then back to kl, apply another one for april 2019 trip.

Or just apply once and i can enter aussie twice with the valid visa?

Thanks