Step Backward creates copies of layer

Hi all,

So I'm trying to determine whether or not this issue is with Photoshop or Wacom software. I'm currently using a Wacom Intuos Pro on Mac, and after a driver update and moving to Photoshop CC 2017, I've had some issues with the undo keystroke. After undoing a stroke with the pen, it will randomly drag the current layer and make a copy of it. It seems to be the triggering the Cmd+alt-drag or Cmd-drag shortcuts, but it's inconsistent as it will often let me step backward once or twice first. I know it's not me accidentally dragging the stylus, because I have taken it off the tablet's surface while using the keystroke and brush icon will still change.

I have reverted back to both an earlier version of Photoshop and Wacom drivers, and the issue seems to persist. Any ideas? Thanks.