SEQ24 can export it's midi outputs as ALSA devices. These show up in the AudioDeviceSelectorComponent inputs list, as expected. However their names are reduced to "seq24". I think they are supposed to be "seq24 1", "seq24 2" etc.
Thats how they look in the aconnect utility, as well as in the sequencer itself.
Also, when you select one of them, all of them become active.