The D6 is currently meh. Most often you already find one of babies good enough, and even if both are so-so, there is a "?" variant. Plus later, on loops, when there are no more babies to select, D6 gets totally useless.
Propose another use: when clicking on dice(after each level obviously), player selects one of babies already obtained, and D6 replaces it with random baby that player doesn't have. This will make item potent in any stage of game, while still random, and interesting due to possibility of getting baby player missed earlier.