More about Exact Slow $k$-Nim

Given $n$ piles of tokens and a positive integer $k \leq n$, the game Nim$^1_{n, =k}$ of exact slow $k$-Nim is played as follows. Two players move alternately. In each move, a player chooses exactly $k$ non-empty piles and removes one token from each of them. A player whose turn it is to move but has no move loses (if the normal version of the game is played, and wins if it is the mis\'{e}re version). In Integers 20 (2020) 1-19, Gurvich et al gave an explicit formula for the Sprague-Grundy function of Nim$^1_{4, =2}$, for both its normal and mis\'{e}re version. Here we extend this result and obtain an explicit formula for the P-positions of the normal version of Nim$^1_{5, =2}$ and Nim$^1_{6, =2}$.