Yes, it is (when using the hardware renderer. The software one doesn't support multi texturing). But the obj-format itself doesn't support multiple texture layers, so you have to do it in code. You can use something like this:
private void reTexture(Object3D obj, String t2, float tileFactor) {
Logger.log("ReTexturing...", Logger.MESSAGE);
PolygonManager pm=obj.getPolygonManager();
int t2Id=TextureManager.getInstance().getTextureID(t2);
int end=pm.getMaxPolygonID();
for (int i=0; i<end; i++) {
int t1=pm.getPolygonTexture(i);
SimpleVector uv0=pm.getTextureUV(i, 0);
SimpleVector uv1=pm.getTextureUV(i, 1);
SimpleVector uv2=pm.getTextureUV(i, 2);
TextureInfo ti=new TextureInfo(t1, uv0.x, uv0.y, uv1.x, uv1.y, uv2.x, uv2.y);
uv0.scalarMul(tileFactor);
uv1.scalarMul(tileFactor);
uv2.scalarMul(tileFactor);
ti.add(t2Id, uv0.x, uv0.y, uv1.x, uv1.y, uv2.x, uv2.y, TextureInfo.MODE_MODULATE);
pm.setPolygonTexture(i, ti);
}
Logger.log("ReTexturing...done!", Logger.MESSAGE);
}
and call it like
reTexture(plane, "layer2", 2f);
However, this method calculates the uv-coordinates of the second layer relative to the first one's. Maybe that's sufficient for you, if you know the size of your terrain. If not, you would have to add some code that calculates the new uv-coords based on the actual coordinates of the vertices. I haven't done this for this simple example, but it should get you started.
When used on the advanced example posted in the wiki, the result looks like this: