Sorry, I will try to illustrate below:
pigeons_and_doves is an acf repeater that collects one set of data with two keys
other_pigeons_and_doves is an acf repeater that collects one set of data with two keys
when combining them into the array with this sort method it is listing them as
pigeons_and_doves key values first
A some name in list (pigeons_and_doves)
Z some name in list (pigeons_and_doves)
X some name in list (pigeons_and_doves)
other_pigeons_and_doves key values first
F some name in list (other_pigeons_and_doves)
B some name in list (other_pigeons_and_doves)
D some name in list (other_pigeons_and_doves)
so when they are run out in the loop that you advised with the usort they are displaying like this: (pigeons_and_doves all at top of list and other_pigeons_and_doves all at bottom of the list)
A some name in list (pigeons_and_doves)
X some name in list (pigeons_and_doves)
Z some name in list (pigeons_and_doves)
B some name in list (other_pigeons_and_doves)
D some name in list (other_pigeons_and_doves)
F some name in list (other_pigeons_and_doves)
INSTEAD OF LIKE THIS
A some name in list (pigeons_and_doves)
B some name in list (other_pigeons_and_doves)
D some name in list (other_pigeons_and_doves)
F some name in list (other_pigeons_and_doves)
X some name in list (pigeons_and_doves)
Z some name in list (pigeons_and_doves)
