Are you referring to the Block Removal + Symmetry dupe glitch? This often affects blocks broken when they are on the centerline of an Odd Symmetry plane, and returns to the player an amount multiplied by the number of planes set, to a maximum of x8.
BTW I found this unintentionally, and have no intent to exploit it. l337 h4x make things less fun, since Ned Noobie can make a fortune selling Ship Cores within several minutes of spawning.