Over driving them can cause over heating, i have just cheap Chinese scanners but one thing i found that lessens the strain is reducing the size of the image so they don't need as much current to move over the available scan area.
one thing with power supplies is for scanners they need both a positive and negative rail with respect to ground, you can do this with two supplies as long as they are identical, a dual output power supply will work as long as they are isolated from each other.
Remember Remember The 8th of November, When No One Stood, but Kneel, In Surrender
In a popular government when the laws have ceased to be executed, as this can come only from the corruption of the republic, the state is already lost. Montesquieu