A.
When packing UN 1760 Class 8 PG III in 1H1 outer packaging, the only choice is to use PI 856 which is a CAO package. Referring to DGR 5.0.1.5.3 for CAO Overpacks, we find that (a) only one package should be in the overpack, or (b) if multiple packages are overpacked, they must be visible and accessible, or (c) 4 particular items are exempt from visibility and accessibility.

The answer to the current question is to make one overpack with the two 1H1 clearly visible and accessible, or to make two Sep rate overpacks each containing one 1H1 with 1L. A shrink wrap is wrapping few layers of translucent plastic sheet, and the packages inside are barely visible and it is far from being readily accessible like the case of a rope or tape-bound packages. Crates are acceptable since the inside is visible and accessible.