This is an example of a non-symmetrical oligomer. There are 2 copies of the receptor and and a single copy of the growth hormone. Similar regions on the receptors bind to two distinct sites on the hormone. The hormone is a four-helix bundle with 2 cross-over connections. The receptor is a two-domain protein. Think about it in terms of dominant-negative mutations.

de Vos, A. M., Ultsch, M., Kossiakoff, A. A.: Human growth hormone and extracellular domain of its receptor: crystal structure of the complex. Science 255 pp. 306 (1992) (PubMed)

3hhr (PDB)