From the Get started with the OKdo ROCK 4C+ 4GB Single-Board Computer Starter kit:
The Starter Kit is supplied with three heatsinks, but there are four components they would fit:
The options for the two square heatsinks (2,3) are obvious, but there are two identical chips which could possibly take the rectangular heatsink (1) !
So where is the rectangular heatsink (1) supposed to go?