Dual HMC Feature not working?

I was pleasantly surprised when I saw the new "Dual HMC" (https://lpar2rrd.com/HMC-dual-setup.php) after we updated to the latest lpar2rrd docker container image.

Unfortunately last Thursday night, the "primary"HMC system died. On Friday morning, lpar2rrd showed a huge gap in the daily graph. Even though the Dual HMC deature was activated and the correct IP was entered, the failover did not happen as expected. Also username and password were set correctly.
To save the situation, I disabled the feature and swapped the IP. Full functionality was restored and data collection was resumed immediately and still works. However, apart from the fact, that there is still the gap, now we are seeing duplicates in the filesystem for the new HMC and the disk usage is approximately 2x the previous usage.

Could anyone please help me out in understanding the situation better?

The current setup:

lpar2rrd 7.31-17 free

perl v5.34.0

rrdtool 1.7.2

18 IBM Power Managed Systems

Dual HMC

Cheers,

Daniel