An array is just a variable that holds a list of values. For your purposes it sounds like you want a loop, in addition to an array.
Use the array to store the names of the copied objects. Use the for loop to copy them at regular intervals. Lets say the interval is every frame for 15 frames. Here's an example:
string $copiedObjects[];
int $currentTime = `currentTime -query`;
int $maxTime = $currentTime + 15;
// store this so its easy to get the original selection back
string $selection[] = `ls -sl`;
for(int $i = $currentTime; $i <= $maxTime; $i++)
{
// select the original selection
// (this way we dont duplicate the duplicates)
select -r $selection;
// step one frame forward in time every time the loop runs
currentTime -edit $i;
// duplicate the object
string $copy[] = `duplicate -rr`;
// the duplicate command returns an array of the duplicate objects
// assuming we only have one object selected, assign the first
// value of the $copy array to the index of the $copiedObjects
// array that matches this loop (the value $i is the index for this
// loop
$copiedObjects[i] = $copy[0];
}
