Molotov cocktails have hit a Keysborough home twice in two weeks.
Greater Dandenong CIU Detective Sergeant Dean Hayes said the first attack on the Latrobe Avenue house occurred about 4am on Monday 26 June.
The victims, aged 53 and 49, woke to a loud bang, smelled fuel or petrol, and went outside to find a small fire in the garden bed outside their window and a smashed glass bottle.
They extinguished the flames, which caused damage to the front of the house.
On Monday 10 July about 3.55am, a Jack Daniels bottle containing accelerant was hurled at their front windows.
The flaming bottle burnt an area of paving and plants.
Det Sgt Hayes said the CFA attended but was not required.
The victims heard a motorcycle leaving the scene.
Det Sgt Hayes urged anyone with information to call Crime Stoppers on 1800 333 000.
