Replicator 2x phantom part

[curious aardvark]

best slicer for a rep 2x is Flashprint.
On install select: creator pro.

Sooo much easier and better than the makerbot nonsense :-)
https://www.flashforge.com/download-center

The only other slicer you could use is simplify3d. But to be honest, for the rep 2x flashprint odes a better job. Also real easy to do dual extrusion.

Your printer uses x3g files and those are - as far as I know - the only slicers that support x3g.

The purge wall is for when you are printing with both extruders.
It ensures that when you change from one extruder to the other that all the plastic is purged (hence the name) from the nozzle not being used. Otherwise it tends to dribble over the print.