I've played a few borg STF's over the last couple of days, and atleast twice that I remember, when you complete the 4/4 objective it spawns in 2 of the command ships instead of one, this makes it virtually impossible to complete the STF correctly.

just for information: that is not a STF its called Red Alert or borg invasion, this encounters have nothing to do with the STF.

I have seen this bug too but its possible to kill both of them but its not inteded that there are two of them.

My apologies, i'm relatively new to the game, thanks for correcting me on the STF thing.

I've never been able to kill them when they double spawn, it's a nightmare for a normal pug group.