The worst of the two fires happened just after 1:30 Thursday morning, at a garage located behind a Third Street residence. No injuries were reported, but two cars and other items inside the garage suffered heavy damage.
Investigators say the fire was believed set in a trashcan located next to the garage.
Assistant Marietta Fire Chief Dan Benson said investigators have several suspects from this fire.
The second of the fires happened just before Midnight, in a dumpster located outside a Second Street business.
Two weeks ago, a car and a van were heavily damaged in two fires in the Marietta College area.