It's very difficult to make any diagnosis of this based on the screenshots alone. It could be a bug in the scoreboard message construction or dispatch, or the client scoreboard message parsing. Or something in between. Or something else entirely.
It's not really a critical bug though, so unless you can reliably reproduce it, I'm not going to spend any time looking at it.
Cheers.
Nobody I speak to has seen this bug in years, and some subsequent changes to the relevant code would logically have led toward its demise. If you encounter this bug on modern servers, feel free to reopen this report. Otherwise, let's go ahead and call it dead.
Created attachment 1081 [details] did you?
Created attachment 1082 [details] dretch in human team, just after connecting STRAIGHT to hummies
Created attachment 1547 [details] another one..
Created attachment 1548 [details] another one.. (bis)