Your dissected maple will have been grafted onto a normal green maple(the 'rootstock').You should be able to see the join(often an ugly bulge) somewhere on the main stem.It's usually near the base but if it's a tall stemmed 'standard',it may be up high under the canopy.If so it's probably unwanted growth from the green 'rootstock' below the join you are seeing and should be removed.

definitely sounds like the rootstock, cut it off asap.