Hmm, das ist sehr interessant – I see this issue elsewhere in this community, with no good answer.
And here, there is an answer “remove them from the network” that seemed to fix a similar problem. Note that I have just posted here, to ask for more details on what it means to “remove them from the network”. I am guessing this means that the two chargers were un-plugged from VE.Direct / Cerbo, and so ONLY visible in Victron Connect app, but I am not 100% certain.