All of the new fruit trees I have planted here are dwarf varieties grafted onto full size root stock. The root stock is chosen for the quality of its root growth and its resistance to disease and the grafted stock is chosen because of its fruiting abilities. This means a compact tree with a vigorous and healthy root system and, hopefully, lots of fruit.
When I was feeding and mulching the other day I noticed that the apricot tree had two different leaves on it. The root stock had sprouted below the graft and if left, it would take over.
I have since cut off the rogue foliage close to the stem and all should be well.