Last spring, after doing a lot of research about Avocado varieties, I finally planted 2 avocado trees: a Zutano and a Lamb Hass. I don't have a lot of space, so I planted them fairly close together... I hoped they would grow at the same rate and I would be able to prune them to grow nicely together. Unfortunately, they are not growing at the same rate... in fact, the Zutano isn't growing at all. Meanwhile the Lamb Hass has taken off. It grew 2 feet already and looks amazing while the Zutano is sad and pale. I don't know what to do as I have been treating the trees equally. The Lamb Hass does get a little more sun, but if the Zutano would just grow a bit taller it would get a ton of sun.
Does anyone have any idea about what I should do? Is there any saving the Zutano or should I replace it (with maybe a taller Zutano)? Should I prune the Lamb Hass until the Zutano catches up? If the Lamb Hass takes over the space, I won't have a pollinator for it. There is no other space I could put an avocado.

Thanks in Advance!