The stem encircled in yellow here is the scion/grafted cultivar, the stem you want to grow and flower (because that's what you bought it for)
The others are stems growing from the rootstock, which is an entirely different variety (most likely an ordinary wild species) that provides disease resistence, vigour or whatever. This is NOT what you want, so these need to be cut off as soon as they appear (it's most likely an annual job too...)
