Memory leak in PCMetrics class

[CMExile]

My team is using parallel-consumer in production, and we observed increasing memory usage over time in all of our services.
After monitoring the heap, we found that this stack trace was responsible for 96% of the heap size after 3 days of uptime:

This is reproducible locally. Whenever the parallel-consumer attempts to commit its offsets, it creates two new timers and adds them to the registeredMetrics list in PCMetrics, even if the exact tag combination already exists.

Keeping track of the registeredMetrics list shows this after 10 minutes (With a 1 second commit interval):

Changing the list to a set seems to fix the issue, but not sure if a more sophisticated method would be preferred.