ArcPy Slope Script - Trouble Saving

Question

I have an ArcPy script that applies the slope function to raster files in ArcGIS. I tried running the script with two raster files in the table of contents, and the script runs, but only saves one layer and loads it into the table of contents. I think that the script is overwriting, and only saving the last file. Here is my script:

Answer 1

How about this ... EDIT: This actually works now. It adds both layers at the bottom.

import arcpy
from arcpy import env
from arcpy.sa import *
#comment
env.workspace = "C:\DEM Files"
outWorkspace = "C:\DEM files\OUTPUT"
MXD = arcpy.mapping.MapDocument("current")
df = arcpy.mapping.ListDataFrames(MXD, "Layers")[0]
# Not sure what this line I skipped is doing for you
# rasters = arcpy.mapping.ListLayers(MXD, "", df) #don't do this
rasters = arcpy.ListRasters("*", "TIF")
n=0
for layer in rasters:
    n+=1
    # took out inRaster variable and used layer directly
    outMeasurement = "PERCENT_RISE"
    zFactor = 1
    outSlope = Slope(layer, outMeasurement, zFactor)
    outLayer = str(outWorkspace) + "\\SLP" + str(n)
    outSlope.save(outLayer)
    addLayer = arcpy.mapping.Layer(outLayer)
    arcpy.mapping.AddLayer(df, addLayer, "BOTTOM")
MXD.save()
del MXD