Why two field gates hung together may not make a pair.
You want a pair of 5 bar gates hung together? This gives the benefits of smaller gate swinging arcs and is good with uneven ground.
However hanging two smaller wooden field gates (0.9m up to 2.1m width) will not make a "mirror pair" of fieldgates due to the single bracing strut showing on the front of the gate the same for both gates.
Choosing a pair of 2.4m gates (or larger) is fine as there are two bracing struts meeting together at the top of the gate in the middle so the gates look fine when hung together.
It is possible to have a second gate manufactured the other way - however this is a special build - ask the office for manufacturing time and costs.