Can Polyend Tracker send out MIDI sequence and record it using audio input at the same time?

Yes, it is possible to use the Tracker to sequence an external synth using MIDI channel sends and then record that audio back into Tracker while it is playing the pattern.

Go to Sample Recorder, press the Record screen key, and then press the dedicated Play button to start and stop the sequence. This will start your MIDI sequence playback while simultaneously sample recording from the audio input connector.

Keep it up and have fun with your Tracker!