Departing from my previous answer from the rules perspective, Jeremy Crawford has answered this question in a tweet:
Airatome118 @Airatome
@JeremyECrawford Can Warding Bond have multiple active casts if mats are fulfilled? 3 SETS of rings divided out = 3 ongoing separate spells?
Jeremy Crawford @JeremyECrawford
You can maintain warding bond on multiple creatures at once if you have a pair of the rings for each casting. #DnD