Question

if you have two separate current carrying loops of wire in the xz plane, one at y=0 and one at y=L. And each loop carries a current of I in the same direction.

how do you calculate the magnetic field across the y-axis, and what if we have n loops in each of the separate loops?

Answer 1

You can find derivations of this configuration (one coil on top of another, sperated by a certain distance) if you Google the subject "Helmholtz coil". I do not understand what you mean by "loops inside of loops"